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303 records found
1.
Sémoroz, A., L. Strezov, et al. (2002). "Orientation Domains and Texture in Hot-Dipped Galvanized Coatings." Metallurgical and Materials Transactions A 33A(No. 8): 2695 - 2701.
The crystallographic orientation of galvanized coatings (Zn-0.2Al-0.15Sb in wt pct) has been characterized by Electron-Backscatterd Diffraction (EBSD) and optical microscopy. While 80 pct of the nucleation spots in the coating give rise to single-crystal Zn grains, it has been found that about 20 pct of them give rise to two or more orientation domains, each having a specific crystallographic orientation. For such "polycrystalline Zn grains," the orientations of the domains are crystallographically related: they have a dense crystallographic direction (<1010>,<1120> or <0001>) in common. Moreover, the crystallographic relationships are similar to those observed in snowflakes and can be partially explained by the concept of a coincidence-site lattice (CSL). The EBSD measurements were also used in order to measure quantitatively the cystallographic texture. In particular, it has been evidenced that the (0001) texture of galvanized coatings is the result of two contributions: (1) the nuclei are preferentially oriented with the basal parallel to the coating plane (33 pct of the grains have an angle between the basal plane and the coating plane smaller than 22.5 deg), and (2) the grains having the basal plane parallel to the coating plane grow faster (these grains represent 43 pct of the coating surface). This reinforcement of the texture during growth is in agreement with that predicted by growth models, which take into account the effect of the interfaces.
2.
Sémoroz, A., Y. Durandet, et al. (2001). "EBSD characterization of dendrite growth directions, texture and misorienations in hot-dipped Al-Zn-Si coatings." Acta Materialia 49(3): 529-541.
Al–Zn–Si coatings (55% Al–43.4% Zn–1.6% Si in weight pct) deposited on steel substrates by the hot-dipping process have been analyzed by Electron Back-Scattered Diffraction (EBSD) and optical microscopy. In these 20 μm-tick films, the main growth directions of the dendrites have been unambiguously identified as being the closest to <320> directions. When the surface precisely corresponds to a (001) plane of the grain, the four usual <100> growth directions of fcc metals are replaced by eight <320> directions growing parallel to the coating (eight-fold symmetry dendritic pattern). When the surface nearly corresponds to (101) or (111) planes, six growth directions close to <320> projections result in a six-fold symmetry dendritic pattern. This morphology change is attributed to an intrinsic modification of the interfacial energy anisotropy. On the other hand, crystallographic orientation within a single grain is shown to vary substantially: in very large grains, misorientations as large as 35 deg. have been evidenced. Being spatially correlated to the location in the coating and to the dendritic pattern, these misorientations are explained in terms of systematic lattice spacing variations associated with the specific microsegregation pattern. However, thermal stresses induced upon cooling as a result of differential thermal contraction between the coating and substrate, can also contribute to these misorientations. Finally, it is shown that there is no relationship between the strongly marked texture of the cold-rolled substrate and the random orientation of the grains of the Al–Zn–Si coating.
3.
SØiland, A. K., E. J. Øvrelid, et al. (2004). "SiC and Si3N4 inclusions in multicrystalline silicon ingots." Materials Science in Semiconductor Processing 7: 39-43.
In this study we have investigated inclusions present in certain areas of a multicrystalline silicon ingot cast in industry. The inclusions were retrieved from the matrix by dissolution in HF:HNO3, followed by filtration. We identified the inclusions as b-SiC and b-Si3N4 by using Electron Probe Microanalyzer and Electron Backscatter Diffraction. These inclusions appear to a great extent as large clusters consisting of both types of particles. We also obtained a particle size distribution giving the following diameter range; 75 mmo 80 mass%o385 mm. As the carbide particles tend to grow on the nitrides, the latter seem to act as nucleating centers for carbide precipitation. Several of the analyzed parts resulted in no measurable content by this method, indicating an inhomogeneous distribution.
4.
Sabatier, L., P. Villechaise, et al. (2000). "Electron backscattered diffraction and atomic- force microscopy anaysis of slip bands induced by fatigue in 316L austenitic stainless-steel." Journal de Physique IV 10(P6): 197-203.
5.
Sabin, T. I., G. Winther, et al. (2003). "Orientation relationships between recrystallization nuclei at triple junctions and deformed structures." Acta Materialia 51(14): 3999-4011.
Pure aluminium has been cold rolled and partially annealed to yield recrystallization nuclei. The orientations present around a number of triple junctions were characterised using the Electron Back Scattered Diffraction (EBSD) technique before and after the annealing, so that a direct comparison could be made between the orientations in the local deformed structure and the nuclei. It was found that triple junctions were particularly good nucleation sites within the microstructure. Approximately half of the nuclei found had orientations that fell within the scatter from one of the original grains and the remainder were rotated about a pole close to <111> relative to a deformed grain.
6.
Saboundji, A., T. Mohammed-Brahim, et al. (2004). "Thin film transistors on large single crystalline regions of silicon induced by cw laser crystallization." Journal of Non-Crystalline Solids 338-340: 758-761.
Large area, 60 µm × 700 µm, single crystalline silicon regions are produced by using a sickle shaped beam of the second harmonic of a cw Nd:YVO4 laser (532 nm). This not obvious technique is discussed here. Moreover, large thin film transistors (channel width to length ratio W/L=63 µm/22 µm) with all the channel area in the single crystalline region are made. Very high performance, with a mobility value larger than 600 cm2/V s, is obtained. However the negative threshold voltage shows the need to control it by a doping of the channel.
7.
Sachtleber, M., Z. Zhao, et al. (2002). "Experimental investigation of plastic grain interaction." Materials Science and Engineering A 336: 81-87.
Aluminum polycrystals with columnar coarse grains are plastically compressed in a channel die. The spatial distribution of the accumulated plastic surface strains is determined by measuring the displacement fields using photogrametry. For this purpose digital stereological image pairs of the sample surface are taken at the beginning and after each deformation step. The displacement field is derived from them by applying an image analysis method based on pattern recognition to the data before and after straining. The three components of the plastic displacement vector field are used to derive the surface portion of the plastic strain tensor field. The microtexture of the specimens is determined by the analysis of electron backscattering patterns obtained in a scanning electron microscope. The experiments are interpreted by comparing them to the corresponding crystal plasticity finite element simulations.
8.
Saha, R. and R. K.Ray (2005). Study of Microstructure and Texture Formation in a (Ti+Nb)- IF Steel after Ultra High levels of Cold Rolling and Annealing. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The formation of crystallographic texture and microstructure in a (Ti+Nb) –IF steel after ultra high levels of cold rolling(CR) and annealing has been investigated. The 98% cold rolled material reccrystallised faster as compared to the 90% cold rolled steel. The strengths of the texture components contributing to deep drawability did not deteriorate significantly even after 98% cold rolling.
9.
Sahal, M., J. Creus, et al. (2004). "Consequences of plastic strain on the dissolution process of polycrystalline nickel in H2SO4 solution." Scripta Materialia 51(9): 869-873.
The effect of plastic strain on dissolution rate in acid solution of nickel is investigated experimentally. A thermodynamic analysis of the modification of solid–liquid balance by the dislocations is used to demonstrate the importance of the adsorption steps and dislocation distribution on the dissolution kinetic.
10.
Sahu, J. K., S. Tarafder, et al. (2004). Fatigue Crack Initiation in a Low-Temperature Isothermally Aged Duplex Stainless Steel. 59th Annual Technical Meeting of the Indian Institute of Metals, India, Chennai, Indian Institute of Metals.
The '475°C embrittlement' of the ferritic phase in a duplex stainless steel affects the fatigue life of the material adversely. In a stress-controlled fatigue loading condition it has been shown that the fatigue crack nucleation is dependent on the operative stress level. Optical image analysis, scanning electron microscopy equipped with electron back scattered diffractometry (EBSD) and orientation imaging microscopy (OIM) has been extensively carried out for these investigations.
11.
Saito, N., M. Mabuchi, et al. (1998). "Effects of the La2O3 particles addition on grain boundary character distribution of pure W." Journal of Materials Science 17(17): 1495-1497.
The effect of La2O3 particles on the grain boundary character distribution of pure tungsten was examined using the scanning electron microscopy-electron backscattering pattern technique. The method allowed grain-by-grain orientation measurements of the specimens. As-annealed W-0.8 mass% La2O3 exhibited a higher distribution of boundaries with lower interfacial energy, as compared with as-annealed pure tungsten. The addition of 0.8 mass% La2O3 particles may have stabilized the microstructure of as-annealed pure tungsten, so that GBCD showed almost no change, even after deformation at elevated temperature.
12.
Saito, N., M. Mabuchi, et al. (1999). "Control of Grain-Boundary-Character-Distribution of Commercial Al-Mg Alloys by Hot Extrusion." Journal of Materials Science 18(1): 41-45.
The effect of La2O3 particles on the grain boundary character distribution of pure tungsten was examined using the scanning electron microscopy-electron backscattering pattern technique. The method allowed grain-by-grain orientation measurements of the specimens. As-annealed W-0.8 mass% La2O3 exhibited a higher distribution of boundaries with lower interfacial energy, as compared with as-annealed pure tungsten. The addition of 0.8 mass% La2O3 particles may have stabilized the microstructure of as-annealed pure tungsten, so that GBCD showed almost no change, even after deformation at elevated temperature.
13.
Saito, N., M. Mabuchi, et al. (1999). "Grain-Boundary-Character Distribution Control of Al-Mg Alloys by Hot Extrusion." Materials Science Forum 304: 579-584.
14.
Sakata, T., H. Y. Yasuda, et al. (2001). "Control of Microstructure and Orientation Distribution in Ni-Al-Based (ß/g') Two Phase Alloys by Thermomechanical Processing." Acta Materialia 49: 4231-4239.
Microstructure and orientation distribution of two phase Ni-Al(ß)/Mi3Al(y') alloys obtained by thermomechanical processing were examined using electron back-scatter diffraction pattern technique. Cylindrical specimens were hot compressed in the ß phase region and subsequently annealed in the (ß/y') two phase region. After the hot deformation, equiaxed ß grains surrounded by high angle boundaries were homogeneously formed due to dynamic recrystallization under adequate condition. Moreover, strong <111> fibre texture parallel to the compressive axis developed in the ß phase because of the lattice rotation during hot deformation. After annelaing in the two phase region, y' phase transformed from ß phase <111>ß fibre texture satisfying the Kurdjumov-Sachs relationship and resulting in the formation of <110>y' fibre texture. Film-shaped y' phase preferentiallyoften precipitated along the ß grain boundaries, and a large number of (ß/y') boundaries were partially coherent. The thermomechanical processing was effective in controlling the crystallography of y' along the ß grain boundaries.
15.
Sakata, T., H. Y. Yasuda, et al. (2003). "Effect of coherency on interphase boundary sliding in NiAl (ß) bicrystals with film-like Ni3Al(y') precipitate along boundary." Scripta Materialia 48: 749-753.
Effect of the crystallography of Ni3Al(y') precipitates along grain boundaries of NiAl(ß) on the interphase boundary sliding of (ß/y') interface was examined using ß bicrystals. Interphase boundary sliding occurred preferentially at incoherent (ß/y') interface and the sliding displacement increased with increasing deviation angle from thr Kurdjumov-Sachs orientation relationship.
16.
Salem, A. A., S. R. Kalidindi, et al. (2002). "Strain hardening regimes and microstructure evolution during large strain compression of high purity titanium." Scripta Materialia 46(6): 419-423.
The sudden increase of strain hardening rates, seen after small strains in titanium, was shown to correlate with the onset of deformation twinning. This result appears to match quantitatively with Hall Petch grain size strengthening. The new twin boundaries appear to reduce the effective grain size.
17.
Salem, A. A., S. R. Kalidindi, et al. (2003). "Strain hardening of titanium: role of deformation twinning." Acta Materialia 51(14): 4225-4237.
The purpose of this study is to investigate the role of deformation twinning in the strain-hardening behavior of high purity, polycrystalline alpha -titanium in a number of different deformation modes. Constant strain rate tests were conducted on this material in simple compression, plane-strain compression and simple shear, and the true stress (sigma)-true strain (epsilon) responses were documented. From the measured data, the strain hardening rates were numerically computed, normalized by the shear modulus (G), and plotted against both normalized stress and epsilon. These normalized strain hardening plots exhibited three distinct stages of strain hardening that were similar to those observed in previous studies on low stacking fault energy fcc metals (e.g. 70/30 brass) in which deformation twinning has been known to play an important role. Optical microscopy and Orientation imaging microscopy were conducted on samples deformed to different strain levels in the various deformation paths. It was found that the onset of deformation twinning correlated with a sudden increase in strain hardening rate in compression tests. The failing strain hardening rate correlated with saturation in the twin volume fraction. In shear testing a much lower rate of strain hardening was found, at all strains, and this correlated with a lower density of deformation twinning.
18.
Salem, A. A., S. R. Kalidindi, et al. (2006). "Strain Hardening Due to Deformation Twinning in α-Titanium: Mechanisms." Metallurgical and Materials Transactions A 37(1): 259-268.
Novel experiments were conducted to elucidate the effect of deformation twinning on the mechanical response of high-purity α-titanium deformed at room temperature. Orientation-imaging microscopy (OIM), microhardness, and nanohardness evaluations were employed in conjunction with optical microscopy and quasi-static compression testing to obtain insight into the deformation mechanisms. Hardness measurements revealed that the newly formed deformation twins were harder than the matrix. This observation is perhaps the first experimental evidence for the Basinski mechanism for hardening associated with twinning, arising from the transition of glissile dislocations to a sessile configuration upon the lattice reorientation by twinning shear. This work also provided direct evidence for two competing effects of deformation twinning on the overall stress-strain response: (1) hardening via both a reduction of the effective slip length (Hall–Petch effect) and an increase in the hardness of twinned regions (Basinski mechanism) and (2) softening due to the lattice reorientation of the twinned regions.
19.
Salishchev, G. A., S. V. Zerebtsov, et al. (2004). Formation of Grain Boundary Misorientation Spectrum in Alpha-Beta Titanium Alloys with Lamellar Structure under Warm and Hot Working. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
20.
Samajdar, I. and R. D. Doherty (1998). "Cube Recrystallization Texture in Warm Deformed Aluminum - Understanding and Prediction." Acta Materialia 46(9): 3145-3158.
The formation of cube {100}<001> recrystallization texture was studied in warm plane-strain deformed aluminum. Recrystallization cube texture intensity increased from 4 to 200 times random, as the true strain was increased from 0.92 to 3.2. The increased cube was primarily due to larger numbers of recrystallized near cube grains, as cube grains had either no or very limited size advantage over grains of other orientations. The origin of cube nucleation was found in the partial stability of existing cube grains which produced thin bands of near-cube oriented deformed material and the lower stored energy of these cube bands. A simple geometrical model is proposed for the prediction of cube recrystallization texture in plane strain deformed f.c.c. metals. The model predicts the frequency of cube recrystallized grains as: NCδR/λC. NC is the number of cube grains per (effective) deformed cube band, δR is the recrystallized grain thickness and λC is the spacing between effective deformed cube bands — all measured along normal direction. NC values were, in material with a low predeformed cube grain frequency, proposed to be either 1 or 2, based on the deformed microstructure. The spacing, λC was obtained as (δo/αC)(1/exp S), where δo is the initial grain size, αC is the initial cube grain fraction and Σ is the true strain. This model was found to work extremely well for λC>δR in aluminum.
21.
Samajdar, I., B. Verlinden, et al. (1997). "γ -Fibre recrystallization texture in IF-steel: an investigation on the recrystallization mechanisms." Materials Science and Engineering A A238(2): 343-50.
Development of recrystallization texture in cold-rolled Ti-bearing IF-steel was investigated using X-ray diffraction, Electron Back Scattered Diffraction/Orientation Imaging Microscopy (EBSD/OIM) and TEM. During cold-rolling, both the alpha (RD//<110>) and the gamma (ND//<111>) fibres were observed to be strengthened, although the increase in alpha was more pronounced. Simulations of the cold-rolling using Taylor type theories demonstrated an approximate predictability of the textural changes. Recrystallization strengthened the gamma, as F (={111}<112>) increased but E (={111}<110>) remained essentially unchanged. A corresponding decrease in alpha, more in H (={001}<110>) than in I (={112}<110>), was also observed. The strong gamma -fibre recrystallization texture was mainly due to the larger numbers (i.e. `frequency advantage') of the gamma -oriented grains, as the gamma grains were no larger than grains of other orientations. TEM studies showed an increase in cell size and a decrease and cell misorientation (which means an increase in stored energy) from H to I to E to F. With the exception of a slight drop from E to F, increase in the Taylor factor always corresponded to an increase in the stored energy. The spread of stored energies, corresponding to inhomogeneities in dislocation substructure, were observed to increase from I implies H implies E implies F. A combination of the higher stored energy and the stronger inhomogeneities in dislocation substructure is possibly responsible for the preferred nucleation behavior causing the frequency advantage for the gamma grains.
22.
Samajdar, I., B. Verlinden, et al. (1998). "Development of Recrystallization Texture in IF Steel: An Effort to Explain Developments in Global Texture from Microtextural Studies." Acta Materialia 46(8): 2751-2763.
23.
Samajdar, I., B. Verlinden, et al. (1999). "Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra Low Carbon Steel." Acta Materialia 47(1): 55-65.
Developments in deformation and recrystallization textures were studied in cold-rolled (50-90% reduction) ultra low carbon (ULC) steel using X-ray texture measurements and orientation imaging microscopy (OIM). During deformation, γ-fibre (ND//<111>) increased between 0 and 50% reduction but then did not change significantly, while α-fibre (RD//<110>) increased progressively from 0 to 90% reduction. After complete recrystallization, however, a steady increase in γ and almost no changes in a were observed with increasing strain. Developments in recrystallization textures were attributed to two parameters: (1) spacings (li, as measured along the normal direction, ND, where i can be a speci®c component of a/g-fibres) of the a/g deformed bands; and (2) their relative ability to form recrystallized grains. While li was determined by the deformation texture and the thicknesses of the deformed grains/bands and naturally decreased with increasing strain, estimations of parameter (2) were obtained from the so-called nucleation factors (Ni, defined as the number of recrystallized i grains per i band - as measured/estimated along the ND). At higher strains, noticeable drops in the Nis of α-fibre were observed. Two plausible causes for such drops were increased stored energy advantages for g bands and orientation pinning in some of the αregions.
24.
Samajdar, I., P. Ahmedavadi, et al. (2005). Grain Boundary Nature and Localized Corrosion in 304 Austenitic Stainless Steel. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The present study had one broad objective – to systematically characterize effects of overall grain boundary nature on localized corrosion, intergranular corrosion (IGC) and stress corrosion cracking (IGSCC), of type 304 (UNS S 30400) austenitic stainless steel. Various combinations of cold rolling and solution annealing, were applied to alter relative the relative concentrations of ‘special’ or low CSL boundaries and to relate them with the local corrosion resistance, IGC and IGSCC, after respective sensitization treatments. It has been shown that both extreme high and low concentration of random (or high energy) boundaries can provide an effective means of control for localized corrosion, degree of sensitization (DOS), IGC and IGSCC, - the improvement in localized corrosion resistance at extreme grain boundary randomization being more effective.
25.
Samajdar, I., P. Ratchev, et al. (1998). "Recrystallization and grain growth in a B2 iron and aluminide alloy." Intermetallics 6: 419-425.
26.
Samajdar, I., P. Ratchev, et al. (2001). "Hot Working of AA1050 - Relating the Microstructural and Textural Developments." Acta Materialia 49: 1759-1769.
An aluminum alloy AA1050 was deformed in plain strain at different hot working conditions. An increase in temperature or a decrease in strain rate reduced the relative drop in cube {001}<100> and the relative increase in rolling texture components of Cu {112}<111> and S {231}<346>, especially apparent at the higher strain. Along with such textural changes, significant differences in hot worked microstructures were observed. The two distinct microstructural features, as observed by polarized light optical microscopy, were grain boundary serrations (GBS) and in-grain inclined lines (IIL), typically observed at an approximate angle of 35° with rolling direction (RD). At higher temperatures and lower strain rates, and correspondingly lower Zener–Holloman factors (Z is similar to10° - 1010 s-1), coarse but nearly equiaxed grain interior substructures and GBS were observed. Interestingly, orientation imaging microscopy (OIM) clearly showed insignificant/non-noticeable differences between the substructures of different orientation components. An increase in Z aligned the grain-interior low angle boundaries at an angle of approximately 35° with RD and at higher Z (Z is similar to 1012 - 1013 s-1) the main microstructural feature was the IILs. Development of in-grain long range misorientation (LRM) was estimated to be the mechanism behind the optical visibility of the IILs. The appearance of IILs had two apparent effects—first the substructures of different orientation components were different, and secondly the stability of cube grains dropped noticeably. Generalizing the IILs or 35° inclined cell walls as plastic instabilities or strain localizations, the observed differences in their relative appearance at different deformation conditions and/or texture components could be explained. When formation of such strain localizations are considered as “necessary” for the reorientation of grain segment(s), the cube stability at low Z deformation could also be understood.
27.
Samet-Meziou, A., A. L. Etter, et al. (2003). Recrystallization Study of a Low Carbon Steel After Tensile Strain. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
Recrystallization and texture formation mechanisms of a low carbon steel have been studied by neutron diffraction, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) after 10% tensile strain. EBSD allows us to characterize the first recrystallization steps. It appears that the recrystallized grains of the γ fibre seem to develop by strain induced boundary migration (SIBM). Moreover, the study of the local orientation of grains, which are consumed during recrystallization, has shown that these grains belong to the α fibre and the the "random" part of the texture. Deformed and recovered microstructures have also been studied by TEM to understand what are the parameters at the origin of grain boundary displacement.
28.
Samet-Meziou, A., A. L. Etter, et al. (2004). Recovery and Recrystallization Study after Low Deformation Amount by Cold Rolling in an IF-Ti Steel. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
The first steps of recovery and recrystallization in an IF-Ti steel after 40% cold rolling have been studied using the Electron Back Scattered Diffraction (EBSD), Orientation Imaging Microscopy (TM) (OIM) and the Transmission Electron Microscopy (TEM). As it is well known, for low deformation amounts by cold rolling, recrystallization texture exhibits the g fiber (ND//<;111>) with a reinforcement of the {111}<110> orientation. In order to understand this {111}<110> development during recrystallization, characterization of the deformed site was performed. Different microstructures were distinguished: lamellar bands for the {111}<112> grains of the γ fiber and coarse elongated grains for the {111}<110> orientation that belongs to the α and γ fibers. Whatever the initial dislocation structure, the recovery step seems to be characterized by coalescence and growth of existing cells in the recovered matrix. Then nucleus growth seems to occur by sub-boundary migration. The first steps of recrystallization mainly take place by continuous growth of subgrains including or not the bulging of grain boundaries.
29.
Samet-Meziou, A., A. L. Etter, et al. (2005). Recrystallization in an IF-Ti steel after low deformation amount by tensile strain. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The first steps of recovery and recrystallization in an IF-Ti steel after 35% deformation by uniaxial tension have been studied by Electron Back Scattered Diffraction (EBSD), Orientation Imaging Microscopy(™) (OIM) and Transmission Electron Microscopy (TEM). Two types of substructure are created after tensile strain: diamond shaped cells for the {111}<110> component and equiaxed cells for {001}<110> component. The recovery is by the decrease of dislocation density inside cells, the refinement of the cell walls, the vanishing of the cell wall, the cell coalescence and the cell growth. Recrystallized grains developed by two main recrystallization mechanisms: the “generalized recovery” and the “bulging”. Both mechanisms are based on continuous growth of subgrains followed or not by the migration of the prior grain boundaries.
30.
Samet-Meziou, A., P. Gerber, et al. (2004). Monte Carlo Modelling of Recrystallization Process in Cold Rolled IF-Ti Steel. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
Recently, some authors have used the Monte Carlo modelling using complete set of experimental data to get a better correlation between experimental observations and calculations concerning recrystallization process. Simulations using Monte Carlo technique have been performed these last years for IF-Ti steels in order to predict the microstructure and the texture evolution after high reduction amounts by cold rolling. On the contrary, in the present work, this evolution is simulated in an IF-Ti steel cold rolled after low deformation amount (reduction amount R= 40%). Microstructure is characterized by Electron Back-Scattered Diffraction and introduced in the model. the quality index of the Kikuchi patterns (EBSD data) is used to qualitatively evaluate the stored energy for each grain. Different hypothesis of nucleation mechanisms have been introduced into the model. It has been shown that the better recrystallization texture correlation between experiment and simulation is obtained by taking into account the nucleation in the low stored energy sites and highly misorientation regions. Finally, a simulation issue was compared with EBSD and TEM experimental results: microstructure, recrystalllization kinetics and Avrami coefficients values.
31.
San Juan, J., P. P. Rodriguez, et al. (2003). Processing of Advanced Shape Memory Materials by Powder Metallurgy. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
Cu-Al-Ni shape memory alloys are promising smart materials, but their ductility has to be improved before they can be used for practical applications. In this work, we have developed a new processing method of Cu-Al-Ni alloys by powder metallurgy, which allows us to improve both the mechanical and the thermo-mechanical properties of these alloys. This improvement is illustrated through a complete study of the microstructure by Scanning Electron Microscopy (SEM) with Electron Back-Scatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM) of an alloy elaborated by powder metallurgy. Martensitic transformation behavior and thermo-mechanical properties have been analyzed by Internal Friction and mechanical testing, respectively.
32.
Sanchez, J. E. J., P. R. Besser, et al. (1997). Microstructure of Damascene Processed Al-Cu Interconnects for Integrated Circuit Applications. Fourth Internation Workshop on Stress Induced Phenomena in Metallizations, Tokyo, American Institute of Physics Conference Proceedings.
33.
Sanchez, J. E., O. Kraft, et al. (1992). "Electromigration Induced Transgranular Silt Failures in Near Bamboo Al and Al-2-Percent Cu Thin-Film Interconnects." Applied Physics Letters 61(26): 3121-3123.
34.
Sandim, H. R. Z. and D. Raabe (2004). An EBSD Study on Orientation Effects during Recrystallization of Coarse-Grained Niobium. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
The recrystallization behavior of coarse-grained niobium depends on the nature of its deformatiuon microstructure. In this regard, a longitudinal section of a high-purity coarse-grained niobium ingot was cold rolled to a thickness reduction of 96% followed by annealing in vacuum by 800°C for 1 hr. Metallographic inspection in cold-rolled and annealed specimens was carried out in a field emission gun scanning electon microscope (FEG-SEM). Microtexture was determined by electron backscattered diffraction (EBSD) coupled to the FEG-SEM. The use (of) this technique has evidenced details of the boundary character and subgrain structure found in partially recrystallized regions. The early stages of primary recrystallization are associated to the presence of high-angle lamellar boundaries found in the cold-worked state. Abnormal subgrain growth has been evidenced as a viable mechanism for nucleation of recrystallization.
35.
Sandim, H. R. Z. and D. Raabe (2005). "EBSD study of grain subdivision of a Goss grain in coarse-grained cold-rolled niobium." Scripta Materialia 53(2): 207-212.
Deformation-driven grain subdivision of three neighboring grains is investigated in 80% cold-rolled coarse-grained niobium using high-resolution electron backscatter diffraction. Particular focus is placed on the study of the deformation-induced grain fragmentation of a Goss-oriented crystal.
36.
Sandim, H. R. Z., A. F. Padilha, et al. (1999). "Grain subdivision and recrystallization in oligocrystalline tantalum during cold swaging and subsequent annealing." International Journal of Refractory Metals and Hard Materials 17: 431-435.
A coarse-grained ingot of high-purity tantalum was deformed by swaging at room temperature to a strain of 1.28. During annealing at 900°C for 30 min two neighboring grains were observed to behave quite differently. Electron backscattering diffraction (EBSD) results show noticeable differences in terms of the misorientations developed in both grains. The grain developing larger misorientations recrystallized much more readily than the other. The result is interpreted in terms of the differences in grain subdivision into strongly misoriented regions.
37.
Sandim, H. R. Z., J. F. C. Lins, et al. (2002). Microtextural Inhomogeneity during Thermomechanical Processing of Coarse-Grained Niobium. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
A high-purity coarse-grained niobium ingot was 80% cold rolled in multiple passes. The microstructure of this ingot consists of very coarse columnar grains with sizes in the range of centimeters. Three grains were chosen and investigated in detail concerning their microstructure, stored energy (hardness) and deformation microtexture. Afer subsequent vacuum annealing at 1200°C for 1 h, distinct recrystallization microtextures are found in these grains. Microtexture was detrmined using electron backscatter diffraction (EBSD) in cold-worked and annealed states. Significant lattice rotations are observed within individual grains mainly due to the presence of deformation heterogeneities. Recrystallization texture and grain size vary from one grain to another indicating orientation effects. In consequence, the microstructure of the resulting plate is very inhomogeneous.
38.
Sandim, H. R. Z., J. F. C. Lins, et al. (2003). "Recrystallization behaviour of a cold-rolled niobium bicrystal." Materials Science and Engineering A A354(1-2): 217-228.
A high-purity coarse-grained niobium bicrystal was 70% cold rolled in multiple passes. Deformation occurred in an inhomogeneous manner in both grains giving rise to a banded structure. In consequence, highly misoriented boundaries were developed in the microstructure in a wide range of misorientations, many reaching about 55 degrees. These boundaries act as effective nucleation sites for recrystallization. The microstructure of both grains was investigated using electron backscatter diffraction (EBSD) in the cold-worked state in order to quantify the misorientations (Psi) associated to these bands. Upon annealing at 800 and 900 degrees C, the new recrystallized grains were nucleated preferentially at deformation heterogeneities and in the vicinity of the prior grain boundary in this bicrystal.
39.
Sandim, H. R. Z., J. P. Martins, et al. (2001). "Orientation Effects During Grain Subdivision and Subsequent Annealing in Coarse-Grained Tantalum." Scripta Materialia 45: 733-738.
40.
Sandim, H. R. Z., J. P. Martins, et al. (2004). In-Grain and Grain-to-Grain Textural Inhomogeneities in Coarse-Grained Tantalum. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
The recrystallization behavior of coarse-grained tantalum deformed at large strains is strongly dependent on its deformation microstructure. In this regard, a longitudinal section of a high-purity coarse-grained tantalum ingot obtained by double electron beam melting (EBM) was rolled at room temperature to thickness reductions varying from 70 to 92% followed by annealing in vacuum at 900 and 1200°C for 1 hr. Micrsostructural characterization was performed in cold-rolled and annealed specimens using scanning electron microscopy (SEM) in the backscattered mode (BSE), electron backscattered diffraction (EBSD), and microhardness testing. Results show that recrystallization of individual grains is strongly dependent on the initial orientation. In consequence, recrystallization kinetics varies noticeably from one grain to another. Inhomogeneous in-grain and grain-to-grain spatial distributions of textures are found in the tantalum plates. Texture components belonging to the so-called g fiber ({111}//ND) are in majority in the rolling plane. The presence of tiny recovered regions in the annealed plate is associated to stable orientations like rotated cube {001}<110>, which are very resistant to recrystallization even at high annealing temperatures. EBSD results also confirm the occurence of growth selection during recrystallization in coarse-grained tantalum.
41.
Sandim, H. R. Z., J. P. Martins, et al. (2005). "Recrystallization of oligocrystalline tantalum deformed by cold rolling." Materials Science and Engineering A 392(1-2): 209-221.
The recrystallization behavior of coarse-grained tantalum deformed at large strains is strongly dependent on its deformation microstructure. In this regard, a longitudinal section of a high-purity coarse-grained tantalum ingot obtained by double electron-beam melting (EBM) was straight cold rolled to thickness reductions varying from 70 to 92% followed by annealing in vacuum at 900 and 1200 cro-defec C for 1 h. Microstructural characterization was performed in cold rolled and annealed specimens using scanning electron microscopy (SEM) in the backscattered mode (BSE), electron backscattered diffraction (EBSD), and microhardness testing. The recrystallization of individual grains is strongly dependent on their initial orientation. Recrystallization kinetics varies noticeably from one grain to another. Even after annealing at 1200 s of the C for 1 h, the microstructure of tantalum sections deformed to 92% predominantly consists of alternating bands of recrystallized grains with distinct size distributions and a few elongated areas marking the presence of individual grains softened by recovery. Results also show inhomogeneous in-grain and grain-to-grain spatial distributions of textures in the rolling plane. Copyright 2004 Elsevier B.V. All rights reserved.
42.
Sandim, H. R. Z., M. J. R. Sandim, et al. (2004). "Annealing effects on the microstructure and texture of a multifilamentary Cu-Nb composite wire." Scripta Materialia 51(11): 1099-1104.
We report the microstructural evolution of a Cu-15%Nb composite annealed from 100 to 1050 degrees C. The microstructure was characterized by scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD). Boundary splitting is the predominant mechanism to explain the spheroidization of niobium. A simple model describing this phenomenon is proposed.
43.
Sano, T., H. Mori, et al. (2004). Femtosecond-laser-driven shock quenching of the high-pressure phase of iron. Fifth International Symposium on Laser Precision Microfabrication, Nara, Japan.
The quenching of the epsilon phase of iron, which has not been observed under a conventional shock compression, was attained using a femtosecond laser. The crystalline structure in a recovered iron sample was determined using an electron backscatter diffraction pattern, an electron diffraction pattern, and a synchrotron X-ray diffraction methods. A small quantity of the gamma phase of iron also existed. Thermodynamic state inside the shock front has to be known because the shock induced phase transition occurs inside the shock front. Therefore, the temperature inside the shock front was calculated using thermodynamic equations. It was found that the epsilon phase was induced by the shock itself but not the phase. The phase was suggested to be induced as an intermediate structure between the alpha - epsilon transition. The femtosecond laser driven shock may have the potential to quench high-pressure phases which has not been attained using conventional methods.
44.
Sarma, V. S., B. de Boer, et al. (2002). Ni and Ni-Alloy Tapes with a Very Strong Cube Texture as Substrates for High Temperature Superconducting Tapes. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Ni and Ni alloys are good candidate substrate materials in the production of coated conductors due to the development of strog cube texture following heavy cold working and recrystallisation. To increase the overall current density of the YBa2Cu3O7-d (YBCO) coated conductor either the superconducting YBCO film thickness should be increased or the substrate thickness should be reduced. As the quality of the YBCO film deteriorates with increasing thickness, the alternative is to increase the substrate thickness. The reduction of the substrate tape thickness is limited by the material strength. In this contribution, two ways of substrate strengthening are proposed. By solid solution strengthening with 12 at. % Cr, the tape yield strength can be enhanced up to a factor of three in comparison to pure Ni. The strengthening is limited by the solute concentration at which the cube texture deteriorates. Another way of strengthening the substrates in by introducing finely dispersed particles into the tape matrix following recrystallisation through internal oxidation of Ni-Al alloys. The room temperature yield strength of these tapes reaches up to three times the value of pure Ni. The present paper reports the efforts in improvong cube texture in Ni, Ni-Al, Ni-Cr, Ni-V, and Ni-Cr-Al alloy substrates of 80µm, 40µm and 20µm thickness and also the tensile properties of these tapes.
45.
Sarma, V. S., B. de Boer, et al. (2003). "On the development of high strength and bi-axially textured Ni-3%W/Ni-10%Cr-1.5%AL composite substrate for coated conductor application." Scripta Materialia 48(8): 1167-1171.
Ni and Ni-base allots are good candidate substrate materials in the development of coated conductors. The present paper reports the development of a high strength (Ni-3%W/Ni-10%Cr-1.5%Al) composite tape of 80 µm thickness with a strong cube texture.
46.
Sarrazin, C., R. Chiron, et al. (1994). "Electron backscattering pattern identification of surface morphology of fatigue cracks in TA6V." Fatigue and Fracture of Engineering Materials and Structures 17(12): 1383-9.
Fatigue crack growth in an alpha + beta titanium alloy (TA6V) with three microstructural conditions is studied in high vacuum at 300 degrees C. The faster growth rates are observed in the material with a low content of primary alpha phase and a fine equiaxed microstructure. Near the threshold regime, a slow crystallographic Stage I-like propagation is observed in the three microstructural types where slip occurs along a single-plane system which develops within the alpha grains. These crystallographic facets are identified using an electron backscattering pattern (EBSP) technique and were found to lie on basal planes. (14 References).
47.
Sasaki, Y., K. Ohkawara, et al. (2005). "Measuring Strains for Hematite Phase in Sinter by Electron Backscattering Diffraction Method." ISIJ International 45(4): 582-586.
Based on the relationship between quantified blurring degree of Kikuchi bands obtained by an electron backscattering diffraction (EBSD) technique and macroscopic strains measured by a strain gauge, the local compression strain SESSD in sinter ore has been evaluated. There is a good linear relationship between the average of SEBSD (denoted by SAVE) and the strain measured by a strain gauge (SMEAS). SAVE-1-9SMEAS From the variation of SEBSD on the distance from the grain boundary, the local strain is found to be mainly distributed in the volume near grain boundaries. It has been confirmed that the local strain SEBSD evaluated by EBSD patterns can be used as an index of local strains.
48.
Sasaki, Y., S. M. Bahgat, et al. (2004). The Surface Rearrangement During Wustite Reduction Within its Existence. 2nd International Meeting on Ironmaking and the 1st International Symposium on Iron Ore, Vitoria Espirito Santo, Brazil, Associacao Brasileira de Metalurgia e Materiais (http://www.abmbrasil.com.br).
Development of the surface rearrangement during the wustite reduction within its range of existence was investigated. The surface orientation of each grain before and after the surface rearrangement was determined by Electron Back Scattering Diffraction (EBSD) measurement and the change of surface morphology was examined by FE-SEM. Base on measured EBSD patterns, the rearranged surfaces were found to be mainly consisted of the combination of the singular planes of {100} and {111} depended on the initial grain orientations. The shape of the rearranged surfaces developed from initial (hkl) plane was found to reflect a particular part of the equilibrium shape polyhedron of simple FCC crystal separated by the (hkl) plane.
49.
Sato, T., B. L. Mordike, et al. (2005). An electron microscope study of intermetallic phases in AZ91 alloy variants. Magnesium Technology 2005. Proceedings of the Symposium Sponsored by the Magnesium Committee of the Light Metals Division (LMD) of TMS with the International Magnesium Association, San Francisco, California, USA, Minerals, Metals & Materials Society.
Rolled sheets of AZ31 magnesium alloys were tensile tested at room temperature. Twinning behavior was observed at various strain levels up to a pint of fracture, using an optical microscope, an orientation imaging microscope and an acoustic emission system. Twinned area was increased in two separate stages with strain. Initial rapid increase was observed near the yield point, due to the formation of wide lenticular twins. This was followed by another rapid increase close to the failure point, due to the formation of narrow banded twins. Acoustic emission (AE) signals also exhibited two separate stages with strain, which enabled us to relate each twin type with FFTed AE signals. The each type of twin will be discussed in light of its role on deformation and fracture mechanisms.
50.
Sato, Y. A. and H. Kokawa (1999). "Preferential Precipitation Site of Sigma-Phase in Duplex Stainless-Steel Weld Metal." Scripta Materialia 40(6): 659-663.
51.
Sato, Y. A. and H. Kokawa (2001). "Distribution of Tensile Property and Microstructure in Friction Stir Weld of 6063 Aluminum." Metallurgical and Materials Transactions 32A: 3023-3031.
Dominant microstructural factors governing the global tensile properties of a friction-stir-welded joint of 6063 aluminum were examined by estimating distribution of local tensile properties corresponding to local microstructure and hardness. Yield and ultimate tensile strengths of the as-welded welds were significantly lower than those of the base material. Postweld aging and postweld solution heat treatment and aging (SHTA) restored the strengths of the weld to the levels of the base material. Elongation was found to increase with increasing strength. Hardness tests showed that the as-welded weld was soft around the weld center and that the aged-weld and the SHTA weld had relatively homogeneous distribution of high hardness. Hardness profiles of the welds were explained by precipitate distribution and precipitation sequences during the postweld heat treatments. The strengths of the welds were related to each minumum hardness value. In a weld having a heterogeneous hardness profile, the fracture occurred in the region with minimum hardness. When a weld had a homogeneous hardness profile, its fracture site depended on both crystallographic-orientation distribution of the matrix grains and strrain tensor of the imposed deformation, i.e., it fractured in the region with a minimum average Taylor factor.
52.
Sato, Y. S., H. Kokawa, et al. (1999). "Microstructural Evolution of 6063 Aluminum during Friction-Stir Welding." Metallurgical and Materials Transactions A 30A(9): 2429-2437.
The microstructural distribution associated with a hardness profile in a friction-stir welded, age-hardenable 6063 aluminum alloy has been characterized by transmission electron micrsoscopy (TEM) and orientation imaging microscopy (OIM). The friction-stir process produces a softened region in the 6063 Al weld. Frictional heating and plastic flow during friction-stir welding create fine recrystallized grains in the weld zone and recovered grains in the thermomechanically affected zone. The hardness profile depends greatly on the precipitate distribution and only slightly on the grain size. The softened region is characterized by dissolution and growth of the precipitates during the welding. Simulated weld thermal cycles with different peak temperatures have shown that the precipitates are dissolved at precipitates higher than 675 K and that the density of the strengthening precipitate was reduced by thermal cycles lower than 675 K. A comparison between the thermal cycles and isothermal aging has suggested precipitation sequences in the softened region during friction-stir welding.
53.
Sato, Y. S., H. Kokawa, et al. (2001). "Microtexture in the Friction-Stir Weld of an Aluminum-Alloy." Metallurgical and Materials Transactions A 32(4): 941-948.
In order to characterize plastic flow during friction stir welding, the microtextures in a friction-stir weld of the precipitation-hardened aluminum alloy 6063 have been analyzed by orientation imaging microscopy (OIM). The base-material plate has a Goss orientation. The weld center region, except for the upper surface, takes a typical shear texture component with two types of orientations. The orientations have a pair of common {111} an <110> parallel to the cylindrical pin surface and transverse direction of the plate, respectively. The typical texture component is also observed around the weld center on the midsection, although it rotates about the plate normal direction. A microtextural analysis after postweld heat treatment has suggested that dynamic recrystallization during friction-stir welding generates the recrystallized grains at the weld center.
54.
Sato, Y. S., M. Urata, et al. (2002). "Parameters Controlling Microstructure during Friction-Stir Welding of Precipitation-Hardenable Aluminum Alloy 6063." Metallurgical and Materials Transactions A 33A(3): 625-635.
The aluminum (Al) alloys 6063-T5 and T4 were friction-stir welded at different tool rotation speeds (R), and then distributions of the microstructure and hardness were examined in these welds. The maximum temperature of the welding thermal cycle rose with increasing R values. The recrystallized grain size of the weld increased exponentially with increasing maximum temperature. The relationship with the grain size and the maximum temperature satisfied the static grain-growth equation. In the as-welded condition, 6063-T5 Al was softened around the weld center, whereas 6063-T4 Al showed homogenous hardness profiles. Different R values did not result in significant differences in the hardness profiles in these welds, except for the width of the softened region in the weld of the 6063-T5 Al. Postweld aging raised the hardness in most parts of the welds, but the increase in hardness was small in the stir zone produced at the lower R values. Transmission electron microscope (TEM) observations detected a similar distribution of the strengthening precipitates in the grain interiors and the presence of a precipitation-free zone (PFZ) adjacent to the grain boundaries in all the welds. Microstructural analyses suggested that the small increase in hardness in the stir zone produced at the lower R values was caused by an increase in the volume fraction of PFZ's.
55.
Sato, Y. S., T. W. Nelson, et al. (2005). "Recrystallization in type 304L stainless steel during friction stirring." Acta Materialia 53(3): 637-645.
The recrystallization phenomenon during friction stirring (FS) of type 304L stainless steel was examined by orientation imaging microscopy. In the stir zone, a (100) fiber texture component containing a dominant orientation was observed from the center to the advancing side. Most grains having this dominant (100) fiber texture component contained a high density of dislocations in the as-processed condition. Post-processed heat treatment (HT) resulted in grain growth, twinning and a change in texture component in most grains having this (100) fiber component. Grains having a different orientation than the (100) fiber component, experienced grain growth and twinning without rotation of orientation during HT. From these results, it was deduced that friction stir processed 304L stainless steel partially underwent static recrystallization following dynamic recrystallization during FS.
56.
Satoh, Y. and K. Iwafuchi (2005). "Crystal orientation analysis of running surface of rail damaged by rolling contact." Wear 258(7-8): 1126-1134.
The crystal orientation in the surface layer of a rail was analyzed by means of X-ray inverse pole figure measurement, electron back scattering pattern (EBSP) analysis and transmission electron microscope (TEM) observation for the rail used in service on a narrow-gauge line for 16 years with an accumulated service tonnage of 160 MGT and damaged by repeated rolling contact with wheels of rolling stock. The specific condition that the {1 1 1} crystallographic plane of the constituent grains is oriented parallel to the running surface in the surface layer of the rail is confirmed through the analysis of X-ray inverse pole figure and EBSP orientation image map. The degree of orientation evaluated by the axis density of the 1 1 1 crystallographic axis varies in the direction of depth from the running surface giving a maximum at about 100 mm from the surface. Based on these results, the 1 1 1 axis density is thought to be a potential parameter to evaluate the degree of the rolling contact damage accumulated in the surface layer of rails used in service.
57.
Satoh, Y. and K. Iwafuchi (2005). "Effect of rail/wheel rolling contact on microstructure in surface layer of rail." Quarterly Report of RTRI 46(3): 178-183.
The rail/wheel rolling contact affects the microstructure of rail steel in the surface layer of rail. The microstructure was investigated from a point of view of the 111 crystal orientation by means of X-ray inverse pole figure measurement and EBSP analysis. The specific condition that the crystallographic plane of the constituent grains is oriented in parallel to the running surface in the surface layer of a rail used in service for 16 years is confirmed through the analysis of X-ray inverse pole figure and EBSP orientation image map. The degree of orientation evaluated by the axis density of the 111 crystallographic axis varies in the direction of depth from the running surface giving a maximum at about 100 µm from the surface. Based on the results, it is conceivable that the 111 axis density could be a potential parameter to evaluate the degree of rolling contact damage accumulated in the surface layer of used rails.
58.
Savoie, J., H. L. Yiu, et al. (2002). Investigation of RecrystallizationTexture Evolution during Annealing of Hot Deformed AA3104 Alloy. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Specimens, taken from hot rolled AA3104 slab, were deformed under plane strain compression conditions. The resulting crystallographic textures, obtained from standard X-ray and EBSD texture measurements, are strongly dependent on the deformation temperatures and strain rates. Two extreme conditions were considered, high Z (low temperature and high strain rate) and low Z (high temperature and low strain rate), which influence the cube texture development during both deformation and annealing. In addition, 3D X-ray Diffraction Microscopy (3DXRD) was utilised to characterise the growth of individual grains within the bulk of the samples deformed at high Z. Nucleation times and growth kinetics wre measured in-situ, and distributions of these from a population of grains were analyzed according to their resulting orientations.
59.
Saylor, D. M. and G. S. Rohrer (1999). Determining relative grain boundary energies from measurements of thermal groove geometry. ICOTOM 12: 12th International Conference on Textures of Materials, Montreal, National Research Council of Canada, Building M-55, Ottawa, ON K1A 0R6, Canada.
The misorientations of 201 adjacent pairs of grains in a magnesia polycrystal have been determined using electron back scattered diffraction patterns. The surface dihedral angles of thermal grooves at the same boundaries were measured by atomic force microscopy. Under the assumption that the surface energy is isotropic, these data can be used to calculate the relative grain boundary energy. When the relative grain boundary energy is correlated to the misorientation across the boundary, it is apparent that small misorientation boundaries have relatively lower energies. At larger misorientations, the grain boundary to surface energy ratio varies from 0.85 to 1.65 and is apparently influenced by the anisotropies of the surface energy and/or grain boundary tangent plane.
60.
Saylor, D. M. and G. S. Rohrer (1999). Measuring the Influence of Grain-Boundary Misorientation On Thermal Groove Geometry in Ceramic Polycrystals.
Electron backscattered diffraction patterns were used to determine the misorientation of 201 adjacent pairs of grains in a MgO polycrystal. The width and depth of the thermal grooves formed by these same grain boundaries were also measured by atomic force microscopy (AFM). By simulating the errors associated with the AFM observations and comparing them with existing data for MgO and Al2O3, it was shown that, under appropriate experimental conditions, surface dihedral angles, relative grain-boundary energies, and surface diffusivities determined from AFM measurements are consistent with data acquired by more laborious techniques. Correlation of the grain-boundary misorientation and thermal groove geometry leads to the observation that grain boundaries with small misorientations, regardless of the rotation axis, have shallow thermal grooves and relatively low grain-boundary energies. Furthermore, numerous boundaries with relatively large misorientations but shallow thermal grooves correspond to special boundaries near coincident-site-lattice (CSL) misorientations. Finally, the data set indicates that factors other than the boundary misorientation, such as anisotropy of the surface energy and the grain-boundary tangent plane, play a role in determining the groove geometry. 28 refs.
61.
Saylor, D. M., A. Morawiec, et al. (2003). "Distribution of grain boundaries in magnesia as a function of five macroscopic parameters." Acta Materialia 51(13): 3663-3674.
A semi-automated method has been used to measure all five macroscopically observable parameters of 4.1 X 106 boundary plane segments making up 5.4 mm2 of boundary area in a hot-pressed magnesia polycrystal. The observations allow a complete description of the distribution of crystal orientations, grain boundary misorientations, and the crystallographic orientations of grain boundary planes. Among the low misorientation angle grain boundaries, there is a preference for tilt boundaries, especially those with boundary plane normals in the <110> direction. At all fixed misorientations, there is a preference for boundaries with a boundary plane normal in the <100> direction. These boundaries are generally asymmetric and occur at least twice as frequently as the average boundary for each fixed misorientation.
62.
Saylor, D. M., B. S. E. Dasher, et al. (2004). "Distribution of grain boundaries in aluminum as a function of five macroscopic parameters." Acta Materialia 52: 3649-3655.
The grain boundary character distribution in commercially pure Al has been measured as a function of lattice misorientation and boundary plane orientation. The results demonstrate a tendency to terminate grain boundaries on low index planes with relatively low surface energies and large interplanar spacings. The most frequently observed grain boundary plane orientation is (1 1 1). However, there are also instances where boundaries terminated by higher index planes have significant populations. For example, certain twist configurations on {1 1w} planes, which correspond to symmetric [1 1 0] tilt boundaries, also have relatively high populations. The population of symmetric [1 1 0] tilt boundaries exhibits an inverse relationship with previously measured energies.
63.
Saylor, D. M., B. S. El-Dasher, et al. (2004). "Measuring the Five-Parameter Grain-Boundary Distribution from Observations of Planar Sections." Metallurgical and Materials Transactions A 35(7): 1981-1989.
A stereological method is described for estimating the distribution of grain-boundary types in polycrystalline materials on the basis of observations from a single planar section. The grain-boundary distribution is expressed in terms of five macroscopically observable parameters that include three parameters that describe the lattice misorientation across the boundary and two parameters that describe the orientation of the grain-boundary plane normal. The grain-boundary distribution is derived from measurements of grain orientations and the orientations of the lines formed where grain boundaries intersect the plane of observation. Tests of the method on simulated observations illustrate that the distribution of boundaries in a material with cubic symmetry can be reliably determined with about 10 deg of resolution from the analysis of 5 X 104 or more line segments. Furthermore, grain-boundary distributions directly observed from serial sections of a SrTiO3 polycrystal are compared to those resulting from the stereological analysis of a single plane. The comparison shows that the stereological method provides a reasonable estimate of the measured distribution. The differences between the directly observed grain-boundary distribution and that derived from the stereological analysis are consistent with the results from the simulation.
64.
Saylor, D. M., D. E. Mason, et al. (1998). The influence of surface and grain boundary tangent plane anisotropy on thermal groove geometry in magnesia. ICGG-3: Third International Conference on Grain Growth, Pittsburgh, PA, USA, Minerals, Metals and Materials Society/AIME, 420 Commonwealth Dr., P.O. Box 430, Warrendale, PA 15086, USA.
We have used atomic force microscopy and electron backscattered diffraction patterns to characterize the geometry and crystallography of thermal grooves on the surfaces of magnesia polycrystals. To quantify the effects of surface energy anisotropy and grain boundary tangent plane on the groove geometry, we have examined only those boundaries that form closed loops separating an included grain from a larger surrounding grain. Since the misorientation across the boundary is the same at all points, we can be certain that the variations in the groove geometry arise from changes in the energies of the bounding free surfaces and/or the grain boundary tangent plane. Measurements of the surface dihedral angle of the groove vary by as much as 26 deg around the circumference of the included grain. This is a significant fraction of the 68 deg variation observed on randomly selected grain boundaries that span a wide range of misorientations. Therefore, we conclude that the influence of the surface and grain boundary tangent plane anisotropy should not be neglected. Finally, the observed systematic variation of the surface dihedral angle with the bounding surface orientation is discussed in comparison to previous results on the anisotropy of magnesia's surface energy.
65.
Saylor, D., A. Morawiec, et al. (2000). "Misorientation Dependence of the Grain Boundary Energy in Magnesia." Interface Science 8: 131-140.
Geometric and crystallographic data obtained from a well annealed magnesia polycrystal have been used to specify the five macroscopic degrees of freedom for 4665 grain boundaries. The results indicate, that for this sample, the five parameter grain boundary character space is fully occupied. A finite series of symmetrized spherical harmonics has been used to approximate the misorientation dependence of the relative grain boundary energy. Best fit coefficients for this series were determined by assuming that the interfacial tensions at each triple junction are balanced. The grain boundary energy function shows Read-Shockley behavior at small misorientations and a broad minimum near the Σ3 misorientation. Furthermore, misorientations about the <100> axis create boundaries with relative energies that are less than those created by misorientations about the <110> or <111> axes.
66.
Saylor, D., A. Morawiec, et al. (2002). Crystallographic Distribution of Low Angle Grain Boundary Planes in Magnesium Oxide. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
We have developed a technique that allows all five macroscopically observable grain boundary degrees of freedom to be characterized for a statistically significant number of interfaces. Using this technique, we have characterized 5 x 106 µm2 of grain boundary plane area in an 0.15 mm3 volume of MgO. The observations demonstrate that there is significant texture in the distribution of boundary planes. Here we compare the observed distribution of grain boundary planes at low misorientation angles (~5°) to the calculated geometrically necessary dislocation content of the same interfaces. Based on the inverse correlation between these two quantities, we conclude that relatively low energy configurations are adopted with the highest frequency.
67.
Saylor, P. M., G. S. Rohrer, et al. (1999). Determining surface energy anisotropy from measurements of thermal groove geometry. ICOTOM 12: 12th International Conference on Textures of Materials, Montreal, National Research Council of Canada, Building M-55, Ottawa, ON K1A 0R6, Canada.
An experimental technique to determine the surface energy of a crystalline solid based on measurements of polycrystalline specimens has been developed. By combining geometric data obtained by atomic force microscopy with orientation data obtained from electron back scattered diffraction patterns, it is possible to index the three interfaces that meet at a thermal groove root. Observations are made at circumferential thermal grooves assumed to be in local equilibrium. Under the assumption that the grain boundary energy of such a groove is independent of its tangent plane, and that the surface energy can be parameterized as a double Fourier series, the unknown coefficients of the surface energy function can be determined by fitting the observations to the equilibrium condition.
68.
Schaeben, H. (2000). Advanced Methods of Texture Analysis. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
The first part provides a unified view of mathematical methods of texture analysis with diffraction data. Diffraction pole figure data are thought of as being discretely sampled from pole density functions, where the recorded intensities are mean values of an orientation density function along great circles. Thus, pole density functions are hyperspherical X–ray transforms of a given orientation density function. The central problem of texture goniometry then is to reconstruct an orientation density function from the experimental pole density data which is physically reasonable and explains the data sufficiently well. To resolve this tomographic inversion problem the duality of its integral and differential representation is employed. Reconstruction methods are surveyed and characterized by the representation of pole density functions which they apply: radial basis function, splines, spherical harmonics, wavelets, and the additional mathematical modeling assumption introduced to counterbalance the loss of information inevitably inherent in the diffraction experiment. Concludingly, diffraction texture analysis is characterized as applied spherical tomography. The second part presents mathematical methods to analyse individual crystallographic orientation measurements. More specifically, the development of statistical methods for spatial orientation data according to the way they were collected will be summarized. The key to orientation statistics is provided by the crystallographic exponential family (CEF). Its properties will be developed and its practical applications will be exemplified, e.g. parameter estimation, texture regression analysis, texture discriminant analysis and spatial statistics. Summarizingly, the methods of spatial statistical analysis of geo-coded orientations provide some prospects of success to proceed from texture analysis to quantitative orientation mapping.
69.
Schaeben, H. and K. G. v. d. Boogaart (2003). "Spherical harmonics in texture analysis." Tectonophysics 370: 253-268.
The objective of this contribution is to emphasize the fundamental role of spherical harmonics in constructive approximation on the sphere in general and in texture analysis in particular. The specific purpose is to present some methods of texture analysis and pole-to-orientation probability density inversion in a unifying approach, i.e. to show that the classic harmonic method, the pole density component fit method initially introduced as a distinct alternative, and the spherical wavelet method for highresolution texture analysis share a common mathematical basis provided by spherical harmonics. Since pole probability density functions and orientation probability density functions are probability density functions defined on the sphere W3=R3 or hypersphere W4=R4, respectively, they belong at least to the space of measurable and integrable functions L1(Wd), d=3, 4, respectively. Therefore, first a basic and simplified method to derive real symmetrized spherical harmonics with the mathematical property of providing a representation of rotations or orientations, respectively, is presented. Then, standard orientation or pole probability density functions, respectively, are introduced by summation processes of harmonic series expansions of L1(Wd) functions, thus avoiding resorting to intuition and heuristics. Eventually, it is shown how a rearrangement of the harmonics leads quite canonically to spherical wavelets, which provide a method for high-resolution texture analysis. This unified point of view clarifies how these methods, e.g. standard functions, apply to texture analysis of EBSD orientation measurements.
70.
Schaeben, H., M. Apel, et al. (2005). 3–Dimensional Fabric Reconstruction from 2–Dimensional Orientation Images. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
3–dimensional (3d) automatic crystal orientation mapping (ACOM) allows to sample parallel 2d section raster images which represent the orientation of crystal grains. The fabric, i.e. the partition of the specimen into 3d crystal grains, can be approximated given its intersections with parallel planes provided by series of 2–dimensional raster orientation images. A method to model the 3d fabric topology and geometry is suggested. In the first step, the different sections have to be corrected for any possible shift in the measurement position. This is most reliably done using a cross–correlation algorithm. Next, an orientation is assigned to each voxel. This is a critical step because the step size in the third dimension is usually not equal to the step size in the planes. Therefore an interpolation procedure is required to fill the voxels in the space between the planes. In this way a 3d orientation image is accomplished by interpolating all 2d raster images in a regular 3d grid called voxet. In the third step, voxels with a common crystallographic orientation are joined to polyhedra partitioning the 3d specimen, where each polyhedron is given in terms of its surfaces, edges, and vertices. At this stage, the polyhedra representing crystal grains exist independent of each other as geometric or graphic objects with their absolute locations in terms of coordinates. Finally, topology is generated as a so–called Map to provide easily accessible information concerning the relative location, i.e. neighborhood relationships of crystal grains. This allows for the fast determination of properties, like the spatial orientation of a grain boundary surface. The procedure is illustrated by an example measured on primary recrystallised silicon steel sheet. Serial sectioning was performed by etching of thin layers of material. After each etch an EBSD map was measured from the same area. Some data on 3d grain size and size distribution are presented and compared to 2d results.
71.
Schafer, B. (1998). Sampling error of texture approximation by individual orientation measurement. Texture and Anisotropy of Polycrystals. Zurich-Uetikon, Transtec Publications Ltd. 273-2: 99-105.
The reliability of the ODF obtained from individual orientation measurement is usually limited by the finite number of data points rather than by the experimental angular resolution which is usually better than 1(0). Hence measures of confidence of relevant distribution parameters are highly demanded for texture interpretation. Starting from the multinominal distribution, estimates of the empirical density distribution function and the C coefficients as well as their variances are given. Furthermore estimates of the optimum 1 value for series truncation and reasonable choices of smoothing parameters can be derived from the standard deviations of the C coefficients. Computer simulations on model textures have been carried out to confirm the results. The empirical distribution parameters as a function of sample number are in good accord with those predicted by theory.
72.
Schafer, R., B. E. Argyle, et al. (1993). "Grain Influences on Domains and Read-Back Pulse Distortions of Ferrite MIG Heads." IEEE Transactions on Magnetics 29(6): 3876-3878.
73.
Schafler, E., I. Kopacz, et al. (2005). "Texture of equal channel angular pressed Cu investigated by electron back scatter diffraction and X-ray diffraction." Kovove Materialy 43(6): 422-431.
The texture evolution of copper during route A and C - ECAP has been measured by standard X-ray technique as well as determined by electron back scatter diffraction, the latter monitors also the grain shape changes and the fragmentation during the high strain deformation. The orientation distribution functions were compared and discussed with respect to the subgrain division. With each pass of route A a further elongation and rotation of the grains is observable, while the alternating shear direction when processing route C results in roughly equi-axed grains. The high imposed strains cause formation of new boundaries subdividing the old grains. With proceeding deformation the increasing misorientation in this subgrain structure leads to further fragmentation of the material, what accounts for the good correspondence between microtexture determined by EBSD on relatively small areas and macrotexture obtained by XRD.
74.
Schafler, E., L. Tarkowski, et al. (2005). "Texture evolution and microstructure of ECAP Cu determined by XRD and EBSD." Archives of Metallurgy and Materials 50(2): 435-443.
The equal channel angular pressing (ECAP) as a method of severe plastic deformation imposes high strains to the materials deformed. The consequence is the crystal fragmentation of the material leading to an ultrafine or even nanograined structure yielding various improved properties. Since ECAP can achieve extraordinarily high plastic strain of material, the evolution of crystallographic texture, misorientation distribution and crystal size are of high interest. These properties have been investigated for the example of room temperature deformation by ECAP under variation of pass number (up to 16) as well as route type (A, Bc and C). Based on the orientation distribution function (ODF) in the Euler angles space, the development of texture and periodical changes of its main components has been analyzed. The evolution of misorientation of the deformed microstructure accompanied with its fragmentation was observed by electron back scatter diffraction (EBSD) in terms of changeable parameters of deformation. The obtained orientation maps also reflect the influence of the macroscopic shear conditions on the development of microstructure.
75.
Schlei, B. R. (2002). "Region-enclosing contours from edge pixels." Proceedings of the SPIE - The International Society for Optical Engineering - Vision Geometry XI 4794(1): 63-70.
In the fields of digital image processing, computer vision and pattern recognition, the application of edge detection algorithms is important for the extraction of multiple touching regions in images. However, the enclosure of the regions with discrete contours is not straightforward in general. A novel region-enclosing contour method is therefore proposed in this paper. Topics such as (dilated) contour enclosure of edge pixels in 2D binary images, geometric thinning (skeletonization) of shapes, gap closure in contour networks, and down-sampling of contour supporting point sets are discussed and new techniques are proposed for the first time. Most of the newly found techniques depend heavily on the application of a Delaunay tessellation. The resulting set of novel shape processing tools is applied here to an image taken from a metal surface in electron backscattered diffraction experiments in order to provide an accurate characterization of grain boundaries.
76.
Schmütza, J., E. Brinksmeiera, et al. (2001). "Sub-surface deformation in vibration cutting of copper." Precision Engineering 25: 218-223.
Vibration cutting processes yield significantly reduced cutting forces and increased shear angles. However, little research has been dedicated to the impact of vibration diamond cutting on the sub-surface integrity of machined polycrystalline metals. Therefore, the depth of plastic deformation in machined OFHC-copper samples was determined by metallographic methods. Moreover, orientation imaging microscopy (OIM) is introduced as a new SEM-technique, which allows one to visualize the distribution of local crystallographic orientations and plastic deformations. The work-hardening is to be studied by AFM-nanoindenting, which has been applied to different metals in order to prove the reliability of this technique.
77.
Schmerling, M., D. Finello, et al. (1981). "Auger-Electron Spectroscopy as Applied to the Study of the Fracture-Behavior of Materials." Scanning Electron Microscopy(P1): 431-438.
78.
Schmidt, E. and S. Sridhar (2004). "A study of Austenite Decomposition Combining Direct Visualization through Confocal Microscopy and Orientation Imaging." TMS Letters.
While much attention has been paid to the microstructure of Fe-C alloys resulting from a wide range of heat treatments, most of the understanding is limited to characterization techniques that depend upon discerning the final structure at higher and higher resolutions with electron microscopical equipment, which often only allow a posteri observations. Experiments utilizing a hot-stage confocal scanning laser microscope (CSLM) have been carried out to observe these transformations in real time at the temperatures at which they occur. The resulting videographs can be compared to orientation images of the same surface in order to relate growth rates and morphologies to crystallographic orientation. Results suggest that the use of serial sectioning techniques to reconstruct the region below the surface in three dimensions, combined with OIM and CSLM data as produced in this study, will allow for the formation of a useful 3D kinetic model.
79.
Schmidt, E. D. (2004). "A combined study of solid state phase changes in steel through confocal microscopy and orientation imaging." JOM 56(11): 327.
A Confocal Scanning Laser Microscope (CLSM) has been used to directly observe austenite formation during heating and ferrite formation during cooling. The final microstructure can then be analyzed via electron backscaterring diffraction (EBSD) to determine the crystallographic orientation relationship of the various ferrite morphologies - primarily allotriomorphic and Widmanstatten. These ferrite orientations can then be used to determine the prior austenite grain locations and orientations. A detailed and accurate analysis of the phase change kinetics is then possible by comparing direct observations and orientation relationships from the exact same location. The effect of heating rate, cooling rate, annealing temperature, annealing time, and atmosphere have all been explored in this study.
80.
Schmidt, N. H. and N. O. Olesen (1989). "Computer-Aided Determination of Crystal-Lattice Orientation from Electron-Channeling Patterns in the SEM." Canadian Mineralogist 27(MARCH): 15-22.
The paper presents the major steps of a mathematical procedure that permits the simulation of Electron Channeling Pattern (ECP) maps of any mineral species for which unit-cell constants, the atomic species and their equivalent positions are known. the basis of the calculation is the Bragg equation, the structure factor F, and the atomic scattering factors of the atomic species. Simulated spherical ECP maps for chromite and quartz are presented and compared to traditional ECP maps, whcih were constructed from ECP photomicrographs, with good results. The fraction of the ECP sphere that covers all possible orientations of a crystal is discussed for all 32 point groups. It is shown that Laue-group symmetry is the determining factor, which results in a loss of "resolution" in certain point groups. The ECP simulation leads to the creation of a software package CHANNEL, which permits rapid ECP-pattern recognition and lattice-orientation determination, in principle without the need for previous construction of an ECP map.
81.
Schmidt, N. H., J. B. Bilde-Sorensen, et al. (1991). "Band positions used for online crystallographic orientation determination from electron back scattering patterns." Scanning Microscopy 5(3): 637-643.
A computer procedure for on-line analysis of electron back scattering patterns (EBSP) has been developed. An experimental EBSP is computer recorded and displayed on a computer monitor. The user identifies the positions of at least two bands in the EBSP with a cursor. Based on this input the computer calculates possible crystallographic orientations. The corresponding EBSPs are simulated and superimposed on the experimental EBSP. The correct crystallographic orientation is determined from a comparison between the experimental and simulated EBSPs. Typically, the analysis takes a 10-30 seconds per pattern. Advantages with the present procedure are that it can be applied for any crystal symmetry, that it requires no knowledge about electron diffraction maps, that it can be used for EBSPs with relatively low contrast, and that the indexing is very precise. For relative orientation measurements the accuracy is found to be within range 0.05 degree -0.20 degree, whereas, for repeated measurements of a given grain after complete remounting of sample and EBSP equipment, it was determined to be 0.5 degree. Furthermore, the procedure facilitates fully automatic pattern recognition. (Author abstract) [References: 17]
82.
Schmied, M. and S. Mitsche (2004). Channelling contrast by focused ion beam and EBSD - two complementary techniques. European Microscopy Congress 2004, Antwerp, Belgium.
83.
Schmocker, M., M. Bystricky, et al. (2003). "Granular flow and Riedel band formation in water-rich quartz aggregates experimentally deformed in torsion." Journal of Geophysical Research 108(B5): 2.1-2.16.
We have investigated the influence of aqueous fluid on the deformation behavior of fine-grained quartz aggregates in the semibrittle field by deforming wet Dover flint to high shear strains in torsion. Tests were carried out under drained conditions at temperatures of 1250 and 1300 K, 350 MPa confining pressure and constant twist rate. Heat treatments prior to deformation were performed at 1300 K for different amounts of time at confining pressures of 150 or 350 MPa, resulting in an initial dilation with an isotropic distribution of water-filled pores, followed by compaction with continuous reduction in porosity and grain growth. Deformation of the heat-treated samples reached steady state behavior until a shear strain of y = 0.2 followed by sudden hardening stages for shear strains up to y = 2.5. Deformation was mainly accommodated within the samples by granular flow. During steady state deformation, the pores redistributed anisotropically in planes oriented at ±25° to the maximum principal stress direction omega1. Hardening was associated with the interconnection of pores to form continuous bands in a synthetic R1 (Riedel) orientation, with no discernible lateral offset along them. These R1 bands served as fluid pathways enhancing local drainage of their surrounding, thus causing hardening by decrease in pore pressure. Two samples were unloaded at a shear strain of y = 1.3 and 2.5, respectively, and reloaded after 0.5 hours at the same deformation temperature and confining pressure. Subsequent deformation occurred primarily by displacement along the existing R1 bands.
84.
Schneider, A. and J. Zhang (2005). "Orientation relationship between a ferritic matrix and κ-phase (Fe3AlCx) precipitates formed during metal dusting of Fe-15Al." Intermetallics 13(12): 1332-1336.
An Fe-15 at.% Al alloy has been exposed to a strongly carburising CO–H2–H2O gas mixture under metal dusting conditions. Cementite (Fe3C) was detected to be present only in the coke which is a reaction product of the high-temperature corrosion metal dusting. Needle- or plate-like κ-phase (Fe3AlCx) precipitates close to the surface were identified by means of electron back-scattered diffraction (EBSD). EBSD analyses of several precipitates and neighboured matrix areas indicate a Nishiyama– Wassermann orientation relationship between the κ-phase precipitates and the α-Fe(Al) matrix.
85.
Schneider, B., C. Bouchet, et al. (1996). Identification of phases in corium held at high temperature in a tungsten crucible by SEM, EPMA, ans ESBD. Microscopy and Microanalysis 1996, Minneapolis, MN.
86.
Schneider, J. A. and E. A. Kenik (2005). "Microstructural Influences on the Development and Growth of Small Fatigue Cracks in the Near Threshold Regime." Journal of ASTM International (JAI) 2(1): 1-11.
Orientation imaging microscopy (OIM) is being used to investigate the microstructural influence on small crack growth at the crack tip. Although grain and grain boundary orientations have been reported to influence small crack growth, the effect has been difficult to quantify. OIM uses electron backscattered diffraction (EBSD) patterns in a scanning electron microscope (SEM) to form a spatially resolved map of crystal orientation, providing information on intra- and inter-grain orientation relationships. Mini-extended compact tension (ECT) specimens were machined from an 1100 aluminum cold rolled sheet with a 45° angle, machined notch tip. The specimens were sized to fit into a Philips XL30/FEG SEM equipped with an EDAX/TSL EBSD/OIM system. Initial images were recorded prior to cycling of the mini-ECT specimen. Fatigue testing was conducted at constant amplitude loading in the nearthreshold regime where small cracks are considered to be on the order of the corresponding grain size. The constant amplitude load testing was periodically interrupted to obtain EBSD images. The ability to map an area 800 x 1300 mum in front of the machined notch tip was demonstrated. This study determined that the plastic deformation, which occurs in a zone in front of the crack tip, did not degrade the EBSD image quality. Use of this technique provides the capability to characterize local crystal orientation during deformation processes such as fatigue crack growth.
87.
Schoberl, T. (2004). "Metallographic preparation methods for atomic force microscopy: Atomic force microscopy as a tool for materialography." Practical Metallography 41(7): 321-333.
Atomic force microscopy, when combined with nano-indentation, allows both to image the microstructure and sub-microstructure of materials and to locally determine mechanical properties of the structural elements. An appropriate application of the method presupposes that the samples are prepared in a suitable way. "Classical" preparation methods are commonly resorted to for this purpose. The article explicates the specific requirements made to atomic force microscopy with reference to the preparation of two simple nickel base alloys, and discusses the resulting limitations and sources of defects, particularly in performing quantitative metallography. The article shows the way the methods helps in studying the influence of local hardness and elastic stiffness of individual phase zones on the development of a surface topography during sample preparation by mechanical polishing.
88.
Schreck, M., T. Bauer, et al. (2003). Domain formation in diamond nucleation on iridium. Diamond 2002: The 13th European Conference on Diamond, Diamond Like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide, Grenada, Spain.
In the effort to prepare single crystal diamond films, heteroepitaxial deposition on iridium buffer layers currently offers the most promising route. Domain formation in epitaxial diamond nucleation on Ir(001) surfaces using the bias-enhanced nucleation (BEN) procedure has been studied. Bright areas of up to several microns lateral size with negligible topographic contrast are observed by scanning electron microscopy (SEM) after ion bombardment. When a growth step is applied after BEN, these domains develop into islands of identical shape consisting of epitaxial diamond with a high local area density of oriented grains. Outside the domains the nucleation density is either orders of magnitude lower or the grains are completely non-oriented. The diamond nuclei or precursors which are formed during the BEN step proved to be very stable: They still yielded oriented diamond islands when the samples were stored in air for 1 year before the growth step. Electron backscatter diffraction (EBSD) patterns taken from inside and outside the domains immediately after BEN did not show any significant difference. This allows the conclusion that the modification of the iridium crystal lattice accompanied with diamond nucleation is either very faint or only restricted to a very thin layer at the surface. Kelvin probe force microscopy (KPFM) measurements indicate a reduced work function within the domains.
89.
Schreiber, A., J. W. Schultze, et al. (2006). "Grain dependent electrochemical investigations on pure iron in acetate buffer pH 6.0." Electrochimica Acta 51(13): 2625-2630.
The influence of grain orientation on the electrochemical behaviour of iron in acetate buffer pH 6.0 was analyzed using a capillary microcell. Cyclic voltammetry and simultaneous capacity measurements were performed on the two crystal faces of an iron (1 0 0)/(1 1 1) bi-crystal, on the grain boundary between these two orientations and on several single grains of a coarse grain iron sample. The combination with electron back scattered diffraction (EBSD) yields the surface orientation of the analyzed grains and makes it possible to perform orientation dependent experiments on the polycrystalline metal. Clear differences in the electrochemical behaviour, e.g. in corrosion tendency and oxide formation rate were found between the orientations (1 0 0) and (1 1 1) of the iron bi-crystal and between several grain orientations of the polycrystalline sample.
90.
Schuh, C. A., K. Anderson, et al. (2003). "Rapid assessment of anisotropic surface processes: experiments on the corrosion of Inconel 600." Surface Science 544: 183-192.
We present a general experimental method for rapid characterization of surface processes on crystals of many orientations. By correlating maps of crystallographic orientation (obtained by electron backscatter diffraction methods) with those of surface topography (obtained by atomic force microscopy), we illustrate how a surface property can be elucidated on many off-principle crystal surfaces from a single polycrystalline specimen. For the corrosion of Inconel 600 in a dilute aqueous solution of HCl, we find that corrosion rates scale with the deviation angle of the surface normal from an ideal fi1 11fi direction. The use of atomic force microscopy can also provide mechanistic details about the surface process in question. For Inconel 600, we correlate the surface oxide morphology directly to the orientation of the underlying crystal.
91.
Schuh, C. A., M. Kumar, et al. (2003). "Analysis of grain boundary networks and their evolution during grain boundary engineering." Acta Materialia 51: 687-700.
The goal of grain boundary engineering is to increase the fraction of so-called special grain boundaries, while decreasing the contiguity of the remaining random boundaries which are susceptible to intragranular degradation such as cracking, cavitation, corrosion and rapid self-diffusion. In the present work, we describe a technique for the quantitative experimental study of grain boundary network topology, with an emphasis on the connectivity of special and random grain boundaries. Interconnected grain boundary networks, or "clusters", of either entirely random or entirely special boundaries are extracted from electron backcscatter diffraction data on a Ni-base alloy, and characterized according to their total normalized length (their "mass"), as well as their characteristic linear dimensions. The process of grain boundary engineering, involving cycles of straining and annealing, is found to substantially reduce the mass and size of random boundary clusters. Furthermore, quantitative assessment of the boundary network topology shows that the special grain boundary fraction is a poor predictor of network topology, but that the higher-order correlation derived from triple junction distributions can successfully describe the length scales of random boundary clusters.
92.
Schulson, E. M. and C. G. van Essen (1969). Journal of Physics E 2: 247.
93.
Schultze, J. W., B. Dauepon, et al. (2004). "Corrosion and passivation in nanoscopic and microscopic dimensions: the influence of grains and grain boundaries." Corrosion Engineering, Science and Technology 39(1): 45-52.
In technical applications of polycrystalline metals, the grain structure and role of grain boundaries are of great importance. Electron backscattering diffraction (EBSD) identifies the surface orientation of grains. In combination with microelectrochemical techniques, single crystal experiments can be carried out on polycrystalline metals. Application of AFM (atomic force microscopy), LFM (lateral force microscopy) and dF/ds (force microscopy) can provide complementary information in the nanometre range, e.g. on grain boundaries. As an example, the etching and passivation of Ti (hcp) has been investigated First, a variety of technical samples from different companies were analysed with respect to grain size, orientation, and twins formation. AFM showed different roughnesses on grains (e.g. (0001)>(xxx0)), while dF/ds demonstrated the greater hardness of films on (0001) compared with (xxx0). Grain boundaries between grains of the same and different orientations must be distinguished In iron the topography of grain boundaries (steps, hills, trenches) shows a clear dependence on the polishing procedure and on the orientation of neighbouring grains. (100) orientated grains always show the fastest metal removal during both chemical and electrochemical polishing. These effects can be correlated with different surface packing densities of the relevant crystal faces.
94.
Schultze, J. W., O. Voight, et al. (1999). Single crystal experiments on polycrystalline materials with anisotropy micro ellipsometry AME and electron beam scattering diffraction EBSD. 195th Annual Meeting of the Electrochemical Society, Seattle, WA.
95.
Schwartz, A. J. and W. E. King (1998). "Research Summary: The Potential Engineering of Grain Boundaries through Thermomechanical Processing." JOM 50(2): 50-5.
96.
Schwartz, A. J., D. H. Lassila, et al. (1998). "The effects of tungsten addition on the microtexture and mechanical behavior of tantalum plate." Materials Science and Engineering A 244: 178-190.
Microtexture variations in annealed tantalum and tantalum–tungsten alloy plate materials have been studied by orientation imaging microscopy (OIM) and correlated with the mechanical behavior over a strain rate range of 10-3 s-1 to 3000 s-1. Plates of nominally pure Ta and Ta–W alloys (2.5, 5 and 10 wt% W), near to 6 mm thick were mechanically tested quasistatically in compression and tension and dynamically via a split Hopkinson pressure bar and punch through shear tests. The results indicate that the unalloyed Ta exhibits anomalous mechanical responses such as inverse barreling or hourglassing in compression and multiple necks in tension, whereas the tungsten containing alloys deform homogeneously. OIM indicates severe texture banding in the pure Ta such that the fraction of grains with near <111> normals is very high near the centerline of the plate and decreases toward the surfaces. Large deviations from this generic description occur from specimen to specimen. Microtexture analyses of the Ta–W alloys reveals no significant texture gradients but rather a change in overall texture from a <111> fiber to a <100> cube texture with the addition of 2.5 wt% tungsten. The evidence suggests that the addition of tungsten results in a more uniform texture and thus homogeneous mechanical response.
97.
Schwartz, A. J., J. S. Stölken, et al. (2001). "Lattice rotations during compression deformation of a Ta single crystal." Materials Science and Engineering A 317(1-2): 77-84.
The slip-system symmetry along <011> in body-centered cubic materials is such that the <111> Burgers vectors on potentially active {110} and {112} slip planes lie within a single {011} plane. In the absence of friction, this affords the opportunity for (macroscopically) homogeneous large-strain deformations by compression. The constitutive response of four specimens in the [011] orientation deformed to 10, 20, 30, and 40% engineering strain, exhibited an up-turn in the true stress–true strain curves at approximately 25%. The primary objective of this investigation was to determine the degree of inhomogeneity of the deformation resulting from the platen/sample interface friction, as related to material modeling. To accomplish this, a simple analytical model was adapted and implemented within a 3D finite-element code to simulate the influence of friction on the measured constitutive response and estimate the associated lattice rotations in the specimen corners. Orientation imaging microscopy (OIM) was applied to characterize the lattice rotations and other mesoscopic features of the deformed microstructures. OIM revealed organized patterns of alternating crystal orientation (deformation bands) that evolved as a function of strain.
98.
Schwartz, A. J., M. Kumar, et al., Eds. (2000). Electron Backscatter Diffraction in Materials Science. New York, Kluwer Academic/Plenum.
99.
Schwarz, S. M., E. C. Houge, et al. (2001). "Bicrystal growth and characterization of copper twist grain boundaries." Journal of Crystal Growth 222: 392-398.
Copper bicrystals with twist character were grown using the vertical Bridgman technique. Cu bicrystals were grown such that the grain boundary in each sample had a nominal twist misorientation consisting of either a low angle (10°), a special angle (Σ5=36.87°), or a high angle (458). The grain boundary plane in all cases was (1 0 0). The grain boundaries were grown using single-crystal seeds that were oriented to within ±0.5° using the Laue back-reflection X-ray diffraction method. The misorientation of each twist boundary was characterized using electron backscattering diffraction patterns in a scanning electron microscope. All grain boundary misorientations were determined to be within the limits defined by the Brandon criterion.
100.
Schwarzer, R. (1991). "The Determination of Local Texture by Electron Diffraction." Textures and Microstructures 20(1-4): 7-27.
101.
Schwarzer, R. A. (1990). A Review of the Analysis of Local Texture by Electron Diffraction. Ninth International Conference on Textures of Materials (ICOTOM 9), Avignon, France, Gordon and Breach Science Publishers.
102.
Schwarzer, R. A. (1991). "Texture Analysis by Electron-Diffraction." Steel Research 62(12): 542-547.
103.
Schwarzer, R. A. (1993). "The Determination of Local Texture by Electron Diffraction." Textures and Microstructures 20: 7-28.
104.
Schwarzer, R. A. (1996). Principles of Orientation Imaging Microscopy in SEM and TEM. Frontiers of Electron Microscopy in Materials Science.
105.
Schwarzer, R. A. (1997). "Advances in crystal orientation mapping with the SEM and TEM." Ultramicroscopy 67: 19-24.
106.
Schwarzer, R. A. (1997). "Automated Crystal-Lattice Orientation Mapping Using a Computer-Controlled SEM." Micron 28(3): 249-265.
107.
Schwarzer, R. A. (1998). Crystallography and microstructure of thin films studied by x- ray and electron diffraction. Trends and New Applications of Thin Films. Zurich-Uetikon, Transtec Publications Ltd. 287-2: 23-60.
For the characterization of thin films conventional x-ray and electron diffraction techniques have been modified and dedicated new techniques have been developed recently with special emphasis being laid on unattended operation. They enable the accurate measurement of lattice parameters, crystallographic orientations of individual grains, crystal texture, lattice strain and residual stress. The analysis of local crystal texture in particular is required for the understanding, for example, of anisotropic material properties, nucleation, recrystallization, plastic deformation and failure mechanisms. X-ray diffraction is still the standard technique for averaging over macroscopic specimen areas. On a grain- specific scale crystal texture: analysis and phase discrimination are mainly performed by electron diffraction involving the SEM or TEM by interpreting backscatter or transmission Kikuchi patterns. Pole figures of small areas are obtained from thin foils in SAD or from bulk surfaces in RHEED mode of the TEM. A graphical representation of spatial distribution of grain orientations, texture, and lattice strain in the specimen surface is obtained with pseudo-color maps.
108.
Schwarzer, R. A. (1999). Advancements of ACOM and applications to orientation stereology. Twelfth International Conference on Textures of Materials (ICOTOM 12), McGill University, Montreal, Canada, NRC Research Press.
109.
Schwarzer, R. A. (2000). Automated Electron Backscatter Diffraction: Present State and Prospects. Electron Backscatter Diffraction in Materials Science. A. J. Schwartz, M. Kumar and B. L. Adams. New York, Kluwer Academic/Plenum Publishers: 105-20.
110.
Schwarzer, R. A. (2002). "Phase discrimination by automated BKD." Anal Bioanal Chem 374: 699-702.
Automated backscatter Kikuchi diffraction in the SEM enables rapid discrimination of phases and the automated acquisition of phase-distribution maps at submicron resolution, if the phases belong to different Laue groups and/or if their lattice constants are significantly different. The acquired database can be further used for quantitative determination of phase contents, for construction of crystal orientation maps, for characterization of grain and phase boundaries, for crystal texture analysis on a grain-specific level by calculating pole figures and orientation density functions separately for each phase, and for orientation stereology in general. Pattern-quality maps provide a clear reproduction of the microstructure on a meso-scale level.
111.
Schwarzer, R. A. (2005). "Advances in the Analysis of Texture and Microstructure." Archives of Metallurgy and Materials 50(1): 7-20.
The past decade has seen some remarkable progress in texture analysis. There is no universal method, and the choice depends on the sampled grain structure as well as on the degree of required information. The standard technique for the analysis of global texture is X-ray pole figure measurement and ODF calculation. A significant improvement in speed and accuracy has been achieved by using a two-dimensional area detector. An extension to local texture measurement has been made by developing an X-ray scanning instrument. X-ray diffraction is a gentle method which is well suited for conductive, recrystallized and flat bulk as well as delicate, non-conductive, deformed, and fine-grain specimens. Local texture of extremely deformed or fine-grain materials can be studied by SAD and RHEED pole-figure measurement in the TEM. Texture analysis on a grain-specific scale is performed by automated Kikuchi diffraction (ACOM) in the SEM ("Automated EBSD ") and TEM. TEM investigations are indispensable when microstructural features have to be quantified such as Burgers vectors and deformation systems. (Example materials: copper, magnesium, aluminum.)
112.
Schwarzer, R. A. (2005). "Local texture and back-end defect in hot extruded AZ91 magnesium alloy." Zeitschrift fur Metallkunde 96(9): 1005-1008.
Local texture in hot extruded MgAl9Zn1 alloy has been studied using individual grain orientation measurement (BKD, "Automated EBSD ") in the SEM. In the shaft of a partial extrudate through a circular die orifice, a <0001> ring fiber texture has formed which continuously changes into a spiral fiber texture in the bottom neck. The flow tube of the internal back-end extrusion defect has a distinctly different texture whereby the (0002) lattice planes are preferentially aligned parallel to the radial and the extrusion directions. The formation of this texture is explained by basal glide, the pile-up of the hard billet mantle, and the inhomogeneous metal flow during the extrusion process.
113.
Schwarzer, R. A. and A. Huot (2000). "The Study of Microstructure on a Mesoscale by ACOM." Crystal Research Technology 35(6-7): 851-862.
The benefits of analytical electron microscopy are the correlation of morphology, elemental composition and crystal structure on a submicron scale. Automated crystal orientation measurement (ACOM) in the SEM enables, by digital beam scan, the convenient and fast acquisition of orientation data in selected bulk surface areas grain by grain. Grain boundaries exceeding some tenth of a degree of misorientation are reliably identified. The quality of backscatter Kikuchi patterns is a (semi-) quantitative measure of local plastic deformation. The database can be used for crystal orientation mapping (COM), quantitative texture analysis (ODF, pole figures, MODF), characterization of grain and phase boundaries, and orientation stereology in general from macroscopic areas down to mesoscale.
114.
Schwarzer, R. A. and H. Weiland (1988). Measurement of Local Textures by Electron Diffraction – Comparison with X-ray Texture Analysis. ICOTOM 8, Santa Fe, New Mexico, The Metallurgical Society.
115.
Schwarzer, R. A. and H. Weiland (1988). "Texture Analysis by the Measurement of Individual Grain Orientations – Electron Microscopical Methods and Application Dual-Phase Steel." Textures and Microstructures 8 & 9: 551-577.
116.
Schwarzer, R. A. and J. Sukkau (1998). Automated crystal orientation mapping (ACOM) with a computer- controlled TEM by interpreting transmission Kikuchi patterns. Texture and Anisotropy of Polycrystals. Zurich-Uetikon, Transtec Publications Ltd. 273-2: 215-222.
A system for acquisition and interpretation of transmission Kikuchi patterns with a camputer-controlled PHILIPS EM 430 TEM is presented. It enables interactive as well as well automated determination of individual grain orientations using digital beam scan for ACOM operation. A high-grade integrating CCD camera is mounted on-axis on the bottom flange of the microscope column. Image resolution is 1,024 by 1,024 pixels, the dynamic range is 14 bit With the present setup more than 3,000 orientations can be measured unattendedly per hour.
117.
Schwarzer, R. A. and J. Sukkau (2003). "Automated Evaluation of Kikuchi Patterns by Means of Radon and Fast Fourier Transformation, and Verification by an Artificial Neural Network." Advanced Engineering Materials 5(8): 601-606.
Automated crystal orientation measurement (ACOM) in the scanning electron microscope (SEM) by interpreting backscatter Kikuchi patterns (BKP, automated EBSD) has become a standard tool of quantitative texture analysis in materials science during the last decade. A Radon transformation of the diffraction pattern, in combination with a 1D fast Fourier transformation (FFT), enables the fast extraction of the positions of Kikuchi bands. An artificial neural network (ANN) is further used for the verification of the detected bands since ANN are able to learn and can thus conveniently be adjusted to the specific band profiles. The high-frequency coefficients of the 1D FFT are used to define pattern quality as a measure of lattice imperfection and residual stress of the real crystal structure. (Example: Fe-Ni alloy.)
118.
Schwarzer, R. A., F. Springer, et al. (1996). Crystal Orientation Mapping by Digital Beam Scan and Automated Interpretation of Backscatter Kikuchi Patterns in the SEM. Eleventh International Conference on Textures of Materials, Xi'an, China, International Academic Publishers.
119.
Scott, S. A., M. V. Kral, et al. (2005). "A crystallographic orientation transition and early stage growth characteristics of thin Bi films on HOPG." Surface Science 587: 175-184.
We report on the growth of ultra-thin bismuth films on the basal plane of highly ordered pyrolitic graphite (HOPG) substrates. Scanning electron microscopy and atomic force microscopy have been used to characterize the morphology, and the crystallographic orientation was obtained using electron back scatter diffraction. Low coverage films are comprised of islands with a striped surface morphology, and show the orientation relationship {0112}Bi|| {0001}HOPG with preferred in-plane orientations <1120>Bi || <1010>HOPG. With increasing film thickness, we identify an unusual orientation transformation to the commonly found Bi{0001} (trigonal) orientation.
120.
Seaton, J. and C. Leach (2003). "Local property measurement in PTC thermistors." Acta Materialia 51: 6027-6034.
The local electrical properties of a positive temperature coefficient (PTC) thermistor based on donor doped BaTiO3with additions of Sr, Pb and Ca, have been characterised and correlated with the results of compositional, microstructural and crystallographic analyses. Wavelength dispersive spectroscopy showed a significant depletion in lead near the pellet surface, caused by volatilisation during sintering. Compensation for the lead loss was principally by Ba substitution, with only a small increase in the levels of Ca and Sr. Local resistance–temperature (R–T) measurements showed a slight reduction in switching temperature, together with an increase in the pre-switching resistance, within the lead depleted zone. Electron backscatter pattern (EBSP) analysis revealed a significant proportion of Σ = 3 and 9 grain boundaries, which are reported to be PTC inactive, in the microstructure. The proportion of Σ = 3 grain boundaries was significantly higher in the lead-depleted zone than in the bulk of the pellet.
121.
Seaton, J. and C. Leach (2004). "Conductive mode imaging of thermistor grain boundaries." Journal of the European Ceramic Society 24: 1191-1194.
PTC thermistors undergo a rapid increase in grain boundary resistivity, covering several orders of magnitude, at temperatures just above the Curie temperature, TC, which is associated with a ferroelectric to paraelectric phase transformation. In this study, hot-stage conductive mode scanning electron microscopy has been used to investigate the characteristics of individual thermistor grain boundaries over a range of temperatures around TC. Using the remote electron beam induced current (REBIC) configuration, imaging has revealed EBIC contrast consistent with the presence of negatively charged electrostatic grain boundary barriers for the first time in a commercial thermistor. Not all grain boundaries within the thermistor were found to be EBIC active and the EBIC contrast was only observed at temperatures above TC. EBSP analysis of grain boundary crystallography indicated that the EBIC active grain boundaries were predominantly high angle.
122.
Seaton, J. and C. Leach (2005). "Evolution of low sigma grain boundaries in PTC thermistors during sintering." Journal of the European Ceramic Society 25(12): 3055-3058.
BaTiO3-based positive temperature coefficient (PTC) thermistors undergo a large and rapid increase in grain boundary resistivity at temperatures just above the Curie temperature, Tc. Ample evidence exists for variability in the magnitude and form of the resistivity increase between different grain boundaries, and it has been noted that many of the grain boundaries showing a weak PTC effect have low σvalues when indexed using coincidence site lattice notation. It has also been reported in the literature that, in undoped BaTiO3, there is a strong preference for the formation of Σ=3 grain boundaries in the microstructure, with many more present than would be expected by chance. In the current study, the formation and retention of low Σ grain boundaries in a PTC thermistor based on doped BaTiO3 have been characterised through interrupted sintering experiments. Electron backscatter pattern (EBSP) analysis was used to establish grain boundary misorientation distributions in a series of samples prepared during an interrupted sintering study. A significant proportion of Σ=3, 5 and 9 boundaries was observed, with Σ=3 boundaries being systematically preferred over other low Σ boundaries. Since S=3, 5 and 9 grain boundaries are believed to be PTC inactive, their presence in significant numbers in the microstructure is likely to be deleterious to the overall performance of a thermistor, particularly during transient loading. An increase in the proportion of Σ=3 twin boundaries was noted with sintering time, however, the proportion of S=3 grain boundaries remained fairly constant, although occurring with a higher frequency than would be expected in a random population. The proportion of Σ=5 and 9 boundaries also remained approximately constant during the sintering process, indicating that the density of low Σ boundaries in the microstructure is fixed at an early stage of sintering and is not affected significantly by grain growth.
123.
Seaton, J. and C. Leach (2005). "Formation and retention of low R interfaces in PTC thermistors." Acta Materialia 53: 2751-2758.
The distribution of grain boundary types in a barium titanate based positive temperature coefficient of resistance (PTC) thermistor was established using electron backscatter pattern analysis in a scanning electron microscope. A higher proportion of Σ = 3 interfaces than would be expected from a random grain distribution was observed, together with numerous Σ = 5 and Σ = 9 grain boundaries. All of these grain boundary types are reported in the literature to be PTC inactive, and hence should not contribute to the overall PTC response of the device. The Σ = 3 interfaces were further characterised on the basis of their microstructure as grain boundaries or annealing twins, from which it was established that the proportion of S = 3 grain boundaries in the thermistor increased only slightly during the sintering process, whereas the proportion of annealing twins increased significantly during the first 30 min of soak at the peak sintering temperature. Σ= 3 grain boundaries were found to be immobile during grain growth, in contrast with high angle grain boundaries, which showed considerable migration.
124.
Seaton, N. C. A. and D. J. Prior (2004). Nucleation During Recrystallisation in Ti-SULC Steel. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
This work is part of a PhD study which investigates mechanisms of nucleation during recrystallisation in steels. A specially built SEM with EBSD and heating stage allows us to observe static recrystallisation in situ. Changes in samples of Ti-stabilised ultra low carbon steel heated to 550 degrees C are documented via still images, videos and automated EBSD maps. Recrystallisation begins rapidly but slows down within an hour. A temperature increase to 850 degrees C forces complete recrystallisation. EBSD mapping shows that the `new' grains appear first on the boundaries of deformed {111} grains and have high angle misorientations with the deformed grains, although the new grains are also of {111} type. {111} type deformed grains are recrystallised first due to their higher stored energy relative to {001} grains. Mapping of a section through the sample along the rolling direction reveals intragranular shear bands. Future work aims to look at these sites in more detail to determine their role as sites for nucleation.
125.
Seefeldt, M., L. Delannay, et al. (2001). "Modelling the Initial Stage of Grain Subdivision with the Help of a Coupled Substructure and Texture Evolution Algorithm." Acta Materialia 49: 2129-2143.
The substructure development in f.c.c. monocrystals and polycrystal grains under cold rolling is modelled with the help of evolution equations for the densities of redundant cell wall and non-redundant fragment boundary dislocations as well as of mobile and immobile disclinations in six cell wall and fragment boundary families. The slip rates for the 12 f.c.c. slip systems are calculated by a full constraints Taylor algorithm. The critical resolved shear stresses are derived from the dislocation and disclination densities. Substructure and crystal orientation are updated alternately in each integration step. The model is able to predict cell wall and fragment boundary spacings as well as misorientations in reasonable agreement with experimental data obtained in TEM studies on aluminium. The subset of preferably splitting grains in a polycrystal is found in reasonable agreement with OIM results.
126.
Sehdeora, A. K. (2005). "Study of plastic deformation in AZ31B magnesium alloy by electron backscatter diffraction (EBSD) and in-situ optical microscopy." 44-01: 542 (141 pgs).
Permanent deformation in metals at low temperatures occurs by two mechanisms: slip and twinning. Twinning depends on the orientation of the crystals which make up the alloy with respect to the applied stresses. It is critical in magnesium alloys, and is poorly understood. Polycrystalline magnesium alloys with strong crystallographic texture show considerable anisotropy in their room temperature mechanical properties, because of the limited number of slip and twinning systems available. In this work, in-situ optical microscopy and Electron Backscatter Diffraction (EBSD) have been used to observe twinning during static uniaxial testing of AZ31B extruded rod. The yield stress is higher in the alloy than in commercially pure magnesium having nominally the same grain size and crystallographic texture. The increase in the yield point of the alloy compared with the pure magnesium is due to solid solution strengthening from the Al and Zn. These elements increase the CRSS for basal slip considerably, which results in a large increase in the yield stress. However, the alloying additions do not contribute to enhanced work hardening. The loading and reloading curves in cyclic tension are non-linear, indicating that plastic deformation processes are taking place. The non-linearity is most likely due to the reversible movement of twinning dislocations under the action of residual intergranular stresses. (Abstract shortened by UMI.)
127.
Sekiguchi, A., J. Koike, et al. (2001). "Void formation by thermal stress concentration at twin interfaces in Cu thin films." Applied Physics Letters 79(9): 1264-1266.
A void formation mechanism was investigated in an electroplated copper thin film on Ta/SiO2 /Si. Microstructural observation after thermal cycling indicated that void formation occurred at intersecting points or terminating corners of annealing twins. The calculated stress distribution was compared with experimental results of the void formation tendency. An excellent correlation was found between void formation sites and stress concentration sites. Electron diffraction analysis revealed that most twin interfaces in Cu thin films are incoherent {322} planes. The stress concentration drives diffusion along incoherent twin interfaces of {322} and leads to void formation at twin interfaces and corners.
128.
Semenov, V. N., E. Rabkin, et al. (1998). "The Effect of the Grain Boundary Misorientation on the Kinetics of the Discontinuous Ordering Reaction in Fe-50 at.%Co." Acta Materialia 46(7): 2289-2298.
The kinetics of the discontinuous ordering reaction in the Fe-50 at.% Co alloy has been studied in the temperature range 280 - 400°C. The misorientation parameters for 61 grain boundaries have been determined with the help of the electron backscattering diffraction technique. It is shown that for low-angle grain boundaries with a misorientation angle below 15° and for grain boundaries which were identified as close to the special S3<111>, Σ9<011>, Σ11<011> and Σ17<001> misorientations (here S is the reciprocal density of the coincidence sites in the two misoriented lattices) the reaction rate is very low. Contrarily, the GBs close to the special Σ19a<011> and Σ19b<111> exhibit high reaction rate. The reaction rates for the other large-angle grain boundaries vary considerably from boundary to boundary. This is discussed in terms of the effect of the grain boundary inclination on the observed reaction rate. The migration rate of large-angle random grain boundaries obeys the Arrhenius relationship: n = 2x1014 exp(-132 kJ&bul;mol-1/RT) m/s, where R and T are the gas constant and the absolute temperature, respectively. A model connecting the grain boundary velocity with the relaxation time of the order parameter in the grain boundary and its mobility is suggested.
129.
Semiatin, S. L., D. S. Weaver, et al. (2004). "Deformation and Recrystallization Behavior during Hot Working of a Coarse-Grain, Nickel-Base Superalloy Ingot Material." Metallurgical and Materials Transactions A 35A(2): 679-693.
The deformation and dynamic recrystallization behavior of Waspaloy-ingot material with coarse, columnar grains was established using isothermal uniaxial and double-cone compression tests. Testing was conducted along different test directions relative to the columnar-grain microstructure at supersolvus temperatures (1066 °C and 1177 °C) and strain rates (0.005 and 0.1 s–1), which bracket typical ingot-breakdown conditions for the material. The flow behavior of axial samples (i.e., those compressed parallel to the columnar-grain direction) showed an initial strain-hardening transient followed by steady-state flow. In contrast, the stress-strain curves of samples upset transverse to the columnar grains exhibited a peak stress at low strains, whose magnitude was greater than the steady-state flow stress of the axial samples, followed by flow softening. The two distinct flow behaviors were explained on the basis of the solidification texture associated with the starting ingot structure, differences in the kinetics of dynamic recrystallization revealed in the double-cone tests, and the evolution of deformation and recrystallization textures during hot working. Dynamic recrystallization kinetics were measurably faster for the transverse samples as well as specimens oriented at ~45 deg to the forging direction, an effect partially rationalized based on the initial texture and its effect on the input rate of deformation work driving recrystallization. Despite these differences, the overall strains required for dynamic recrystallization were comparable to those measured previously for fine-grain (wrought) Waspaloy. However, the Avrami exponents (~2 to 3) were somewhat higher than those for wrought material (~1 to 2), an effect attributable to the particle-stimulated nucleation in the ingot material.
130.
Semprimoschnig, C. O. A., J. Stampfl, et al. (1997). "A new powerful tool for surveying cleavage fracture surfaces." Fatigue & Fracture of Engineering Materials & Structures 20(11): 1541-1550.
A new tool is presented to investigate cleavage fracture surfaces. It is based on the combined techniques of crystal orientation measurements using the Electron Back-Scatter Diffraction (EBSD)-technique and 3-dimensional surfaces reconstruction by an Automatic Surface Reconstruction System (ASRS). With this tool we can perform crystallographic fractometry of cleavage fracture facets of polycrystals within the limits of the resolution of a Scanning Electron Microscope (SEM), e.g. we can determine the crystallographic indices of cleavage planes and of directions on such planes.
131.
Semprinoschnig, C. O. A., R. Pippan, et al. (1995). "Micro-Fractography of Cleavage Fracture by EBSP Technology and Computer Assisted Stereology."
132.
Sengupta, J., H.-J. Shin, et al. (2006). "Micrograph evidence of meniscus solidification and sub-surface microstructure evolution in continuous-cast ultralow-carbon steels." Acta Materialia 54(4): 1165-1173.
Hooks and other sub-surface features in continuous-cast ultralow-carbon steel samples were examined using optical microscopy, electron backscattering diffraction, energy dispersive X-ray spectroscopy, and electron probe microanalysis techniques. Special etching reagents revealed dendrites growing from both sides of the line of hook origin. This line was found to represent the frozen meniscus and persisted into the final microstructure, as revealed by grain orientation measurements. A broken hook tip was observed in one micrograph, which explains the characteristic truncated shape of most hooks. Mold powder was found entrapped along the frozen meniscus. These results provide evidence of both solidification and subsequent overflow of the liquid steel meniscus. Thus, the instantaneous meniscus shape governs the shape and microstructure of the final hook, and the extent of the liquid steel overflow determines the shape of oscillation marks. This mechanism has important implications for the entrapment of inclusions and other surface defects.
133.
Senkov, O. N., R. B. Bhat, et al. (2005). "Microstructure and Properties of Cast Ingots of Al-Zn-Mg-Cu Alloys Modified with Sc and Zr." Metallurgical and Materials Transactions A 36A(8): 2115 - 2126 A.
The effect of combined additions of Sc and Zr on the microstructure and tensile properties of the direct chill (DC) cast ingots of developmental Al-Zn-Mg-Cu alloys has been evaluated in this work. The properties in both the longitudinal and transverse directions were determined in as-cast and cast-plus-heat-treated conditions, at room temperature (RT) and cryogenic temperature (CT). Extensive microstructural evaluation was carried out using optical microscopy and scanning electron microscopy, including orientation image microscopy (OIM) by the electron backscatter diffraction (EBSD) technique. The Sc-containing developmental cast alloys showed the tensile properties, which are much better than the properties of commercial cast Al alloys and are similar or even superior to the properties of 7075-T6 alloy forgings. The microstructural evolution, the strengthening mechanisms, the optimum content of the dispersoid-forming elements, and the processing-structure-property correlations are discussed.
134.
Sennour, M., P. H. Jouneau, et al. (2004). "TEM and EBSD investigation of continuous and discontinuous precipitation of CrN in nitrided pure Fe-Cr alloys." Journal of Materials Science 39(14): 4521-4531.
Pure Fe-Cr alloys (1 and 3 wt% Cr) were gas nitrided (NH3, N2, N2O mixture at 823 K). Two modes of CrN precipitation: continuous (fine disc-shaped precipitates) and discontinuous (lamellae-like precipitates) were identified and investigated using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Both types of precipitates presented a cubic NaCl-type structure and Baker-Nutting orientation relationship with respect to the ferritic matrix. A quantification procedure based on TEM images exploitation revealed that the size and the number of the fine precipitates vary inversely with nitriding depth. This result was compared to the profile of micro-hardness. SEM observations showed that only superficial regions in the Fe-3 wt% Cr were transformed by the discontinuous precipitation of CrN. Electron back-scattered diffraction (EBSD) studies of lamella revealed singular initiation and growth features. A qualitative mechanism of lamella initiation and growth is discussed.
135.
Senuma, T., H. Yada, et al. (1990). "Textures of low carbon and titanium bearing extra low carbon steel sheets hot rolled below their AR3 temperatures." Acta Metallurgica et Materialia 38(12): 2673-81.
The textures of warm rolled low carbon and Ti-bearing extra low carbon steel sheets have been investigated using ODF's ECC-ECP (electron channeling contrast-electron channeling pattern) and selected area electron diffraction and the following results were obtained: (1) The main orientation of the low carbon steel sheet was near (113)(110) while that of Ti-bearing extra low carbon steel was near (111)//ND. (2) The recrystallization of the low carbon steel occurred mainly from deformed (100) grains while the main nucleation sites in the Ti-bearing extra low carbon steel were the grain boundaries of the deformed (111) grains. (3) The main orientations of grains recrystallized from deformed (100) grains are (100)(110)-(112)(110) for both steels. (4) The orientation of the grains recrystallized from the deformed (111) grains of the Ti-bearing extra low carbon steel is mostly near (111)//ND and that of the low carbon steel is mainly near (114)(110). This difference is discussed in terms of the influence of carbon in solution on the crystal rotation at nucleation sites. (19 References).
136.
Seo, B. I., N. J. Park, et al. (2004). Nanoscale orientations of ferroelectric BLT films for nonvolatile semiconductor memories. 11th Korean Conference on Semiconductor, Muju, South Korea, Korean Phys. Soc.
Nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues in obtaining uniform electrical properties for realization of high-density memories. In this study, the grain orientations and size distributions of BLT films made by spin-on coatings were examined by FEG-SEM and EBSD techniques. Ferroelectric-domain characteristics were also investigated by a piezoelectric scanning probe microscope to study the dependence of the properties of domain switching on grain orientation and distribution. It is demonstrated that the EBSD technique is successful in characterization of film orientations. Ferroelectric-domain studies indicate that c-axis-oriented grains with plate-like morphology show almost linear dielectric behavior, a- or b-axis-oriented grains (<. 0.1 mu m) with superior ferroelectric properties show ellipsoidal morphology. Consequently, suppression of the plate-like structure through process controls is important for the realization of high-density BLT-based memories.
137.
Seo, B. I., N. J. Park, et al. (2004). Orientation distributions of ferroelectric BLT films for high-density semiconductor memories. Fifth Pacific Rim International Conference on Advanced Materials and Processing PRICM-5, Beijing, China, Trans Tech Publications.
Issues of ferroelectric high-density memories (>64 Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1 mu m/sup 2/ and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study, the grain orientations and distributions of BT-based films by spin-on coatings were examined by an electron backscatter diffraction (EBSD) technique. Ferroelectric domain characteristics by a piezoresponse force microscope (PFM) were also performed to study the dependence of reliabilities on the grain orientations and distributions.
138.
Seo, D.-H., J.-K. Choi, et al. (2000). Ferrite Grain Refinement by Multi-Pass Rolling at Intercritical Temperature in Low Carbon Steel. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
In order to achieve ferrite grain refinement, multi-pass rolling at intercritical region between Ae3 and Ar3 was performed in low carbon steel. The Ar3 temperature of y/α transformation increased with the increase in the reduction of one pass. The specimen of low carbon steel was isothermally rolled at temperature of 800°C with various reduction per pass of 50%, 40%, 30%, and 20% maintaining the total reduction at 75%. It was known from the metallography that the ferrite grains became finer as the amount of reduction per pass decreased. The increase in total reduction of specimen made the ferrite grain finer due to the promotion of nucleation and recrystallization of ferrite in two-phase region by successive rolling.
139.
Seo, H. W., Q. Y. Chen, et al. (2006). "Epitaxial GaN nanorods free from strain and luminescent defects." Applied Physics Letters 88(15): 153124-1-3.
Raman spectroscopy, cathodoluminescence imaging, and electron backscatter diffraction have been used to characterize the GaN nanorods as compared to their supporting matrix. The nanorods are strain free, distinguished from the mechanically and thermally stressed matrix that bears the brunt of all lattice mismatch and thermal strain, strain relaxation, and the related defect generation. This thus allows the loosely attached nanorods to grow to measurable perfection in electronic and crystal structures. The nanorods are crystallographically aligned with the matrix as well as the substrate.
140.
Sevillano, J. G., C. Garcia-Rosales, et al. (1999). Estruca Y Textura De Un Meteorito Metalico de Tipo Octaedrita (Gibeon). VI Reunion Nacional de Materiales, San Sebastian.
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Sevillano, J. G., E. Aernoudt, et al. (1980). "Large Strain Work-Hardening and Textures." Progress in Materials Science 25(2-4): 71-412.
142.
Seward, G. G. E., S. Celotto, et al. (2004). "In situ SEM-EBSD observations of the hcp to bcc phase transformation in commercially pure titanium." Acta Materialia 52(4): 821-832.
This study presents in situ observations of the hep (alpha) to bcc (beta) phase transformation in commercially pure titanium at 882 degrees C using SEM imaging concurrent with crystal orientation determination using EBSD Direct observations of the onset of the phase transformation are presented showing the early stages of the growth of beta plates within alpha grains and allotriomorphic beta along alpha - alpha grain boundaries. Intragranular beta plates have a Burgers orientation relationship (OR) with the parent alpha grain and are lenticular in shape. These plates also have a tent surface relief and surface-traces consistent with habit planes predicted by the phenomenological theory of martensitic crystallography for pure titanium. These features suggest a military component to the growth mechanism. The beta allotriomorphs have a Burgers OR with one of the alpha grains abutting at the boundary, but do not have surface relief characteristic of a military transformation. These are likely to grow by a civilian mechanism. The final stage of the transformation is a process of competitive growth of the two beta forms, with the allotriomorphic beta dominating by virtue of its faster moving alpha - beta interfaces. Grain growth in the beta stability field is more than an order of magnitude faster than that in the alpha field at temperatures near the phase transformation.
143.
Sha, Y. H., X. Y. Gao, et al. (2002). Effects of Electrostatic Field on Recrystallization Texture and Grain Boundary Character Distribution in a Fe-3%Si Alloy. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Effects of electrostatic field on recrystallization texture and grain boundary character distribution (GBCD) in a Fe-3%Si alloy were investigated. It was found that electrostatic field retards transformation of cold rolling texture, while increases the sharpness of the dominant recrystallization texture component {111}<112>. The effect of electrostatic field is more significant in the early stage of recrystallization. Electrostatic field exhibits no obvious influence so the frequencies of low-angle, coincidence and random grain boundary. However, certain special CSL boundaries can be affected. The effect of electrostatic field on recrystallization texture can be attributed to the decrease of vacancy concentration and dislocation mobility and the resultant decrease of grain boundary mobility.
144.
Shaffner, T. J. (2000). "Semiconductor Characterization and Analytical Technology." Proceedings of the IEEE 88(9): 1416-1437.
145.
Shahmiri, M., S. Hosseini, et al. (2005). "Stir-Modification of the eutectic silicon crystals of A356.0 aluminum alloy by mechanical stirring." Metall 59(1-2): 37-42.
The purpose of the present study was to characterize the influence of mechanical stirring (stir-modification) on the morphology of the eutectic Si crystals of the A356.0 alloy. The evolution of the microstructures of the stirred and unstirred cast samples was characterized by optical and scanning electron microscopy (SEM) and the crystallographic orientation relationship was determined by electron backscattered diffraction (EBSD).
146.
Shankaranarayan, H. and S. K. Varma (1995). "Strain-Rate and Grain-Size Effect on Substructures and Mechanical-Properties in Ofhc Copper During Tension." Journal of Materials Science 30(14): 3576-3586.
147.
Shaokai, C., L. Qingyu, et al. (2006). "EBSD and Its Applications in Materials Research." Rare Metals Mateials and Engineering 35, Pt. 3(236): 500-504.
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Shariat, P., T. G. Langdon, et al. (1982). "An Evaluation of the Roles of Inter-Crystalline and Interphase Boundary Sliding in 2-Phase Superplastic Alloys." Acta Metallurgica 30(1): 285-296.
149.
Sheikhali, A. D. and R. Z. Valiev (1990). "Dislocation Analysis of the Coupling of Grain-Boundary Sliding and Migration During the Deformation of Zn Bicrystals." Physica Status Solidi A 117(2): 429-436.
150.
Sheikh-Ali, A. D., F. F. Lavrentyev, et al. (1997). "Sliding Behavior of Σ=9(1(2)over-Bar-12) Symmetrical Tilt Boundary in Zinc Bicrystals." Acta Materialia 45(11): 4505-4512.
Sliding behaviour of the 57° <101(over bar)0> Σ = 9{1 2(over bar)12} symmetric tilt boundary has been studied in zinc bicrystals. The bicrystals have been tested under creep at two different rates of intragranular slip (IS). For all the bicrystals, coupled grain boundary sliding (GBS) and migration is observed, the rates of these processes being similar along the boundary. In the vicinity at one end of the boundary, at a slower rate of IS there is no GBS or migration, and at a greater rate of IS they have negative values. Also, the increasing values of GBS and migration from one end of the boundary to the other is observed. The results obtained have been interpreted in terms of behaviour of grain boundary dislocations, produced as a result of interaction between lattice dislocations and the grain boundary.
151.
Shen, J., Y. Q. Song, et al. (2003). Modelling Hot Deformation of Al-Zn-Mg Alloy. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
Hot deformation of an Al-Zn-Mg alloy was physically modelled by isothermal compression testing on Gleeble 1500 thermal mechanical simulator to investigate microstructure evolution of the alloy during deformation at elevated temperatures and large ranges of strain rates. Electron Back-Scattering Diffraction (EBSD) was conducted to study the evolution of the grain and subgrain misorientation. Evidence of optical microstructure observation and flow stress, as well as microtexture of the alloy, were analyzed. Material constants of the alloy were derived out to validate the relationship between subgrain size of the alloy and Zener-Holloman parameter (Z parameter). The investigation indicated a decrease of flow stress of the Al-Zn-Mg alloy with increase of true strain, revealing the occurrence of strong dynamic restoration during hot deformation. Very fine equiaxed grains, which possess high-angle boundaries and different orientations to the matrix, were found to develop in the alloy compressed at higher temperatures and lower strain rates, implying the activation of geometric dynamic recrystallization in the alloy. The reciprocal of the subgrain size, which formed in the dynamically recovered zones, was found to have a good agreement in a linear relationship with the logarithm of Z parameter, indicating thermal activation dominated in dynamic recovery process of the alloy.
152.
ShengLi, D., M. R. Wisnom, et al. (1991). "The Mechanical Properties of Matrix in Continuous Future 6061 Al Alloy Metal Matrix Composite." Composite Science and Technology 42: 413-427.
153.
Shengquan, C., Z. Jinxu, et al. (2004). "Study of texture and grain boundary character distributions of IF steels." Acta Metallurgica Sinica (China) 40(10): 1045-1050.
The batch annealing and continuous annealing of IF steel sheets have been simulated. Texture, grain boundary character distributions (GBCD) and their relations with secondary working embrittlement (SWE) were investigated by electron back-scatter diffraction (EBSD).The results show that the two kinds of IF sheets are great difference in texture and grain boundary character distributions: (1) Continuous annealing IF sheets have a strong {111} recrystallization texture composed of {111}<110> and {111}<112>, while the batch annealing IF sheets is composed of weak texture of {111}<110>; (2) Large number of Sigma 3, Sigma 13, Sigma 9 and Sigma 11 CSL boundaries produced in continuous annealing IF sheets, while in batch annealing IF sheets Sigma 3 and Sigma 13 CSL boundaries obviously occurred; (3) Low energy boundaries distributed uniformly in continuous annealing IF sheets, while in batch annealing IF sheets low energy boundaries are accumulative, and random boundaries distribute around the low energy boundaries to form a thick network, which leads to the SWE.
154.
Sheng-quan, C., Z. Jin-xu, et al. (2005). "Effect of grain boundary structure on secondary working embrittlement of IF steels." Journal of Iron and Steel Research 17(1): 51-54.
The effect of grain boundary structure on secondary working embrittlement (SWE) of IF steels was studied by electron back-scatter diffraction (EBSD) and TEM. The results show that the cracks nucleate at dislocations jamming at random boundary during deep-draw forming operation, and propagate along high energy continuous random boundary network, which lead to SWE of IF steels. Meanwhile, it has also been demonstrated that a crack can be arrested by low energy boundaries such as low-Σ CSL boundaries and low-angle boundaries.
155.
Shi, L. Q. and D. O. Northwood (1993). "On Dislocation Link Length Statistics for Constant Strain-Rate Deformation." Physica Status Solidi A 140(1): 87-95.
156.
Shi, L. Q. and D. O. Northwood (1994). "Strain-Hardening and Recovery During the Creep of Pure Polycrystalline Magnesium." Acta Metallurgica et Materialia 42(3): 871-877.
157.
Shi, L. Q. and D. O. Northwood (1995). "On Dislocation Link Length Statistics for Strain-Hardening and Recovery During Elevated-Temperature Plastic-Deformation." Physica Status Solidi A 149(1): 213-224.
158.
Shibata, A., S. Morito, et al. (2005). "Local orientation change inside lenticular martensite plate in Fe–33Ni alloy." Acta Materialia 53: 597-602.
The orientation relationship of lenticular martensite (M) with respect to austenite (A) is nearly Greninger–Troiano at the midrib and twinned region but gradually deviates towards Kurdjumov–Sachs near the M/A interface. This change is related to the change in the substructure of martensite and also to the deformation in the surrounding austenite.
159.
Shibayanagi, T. and M. Maeda (2004). "Characteristics of Microstructure and Hardness in Friction Stir Welded 7075 Aluminum alloy Joints." Transactions of the JWRI 33(1): 17-23.
The present study focuses on the characteristics of microstructure in the joint region of A7075 aluminum alloy. A 7075 aluminum alloy plate with a thickness of 5mm was prepared for the joining. The FSW was performed for butt joints of the alloy with a welding speed and rotating ratio of 300mm/min. and 1500rpm, respectively. Microstructures of the joint region were investigated utilizing the OM, SEM and Electron Back-Scatter Pattern (EBSP) methods. Hardness of the joint was measured by the Vickers micro-indentation system. Grain refinement was achieved in the stirred zone of the joint, but the lowest hardness was obtained in this region. Each grain belonging to the same orientation group tended to form "clusters", and some clusters seemed to be lying along the plastic flow caused by the rotation of the pin. Spatial distributions of microstructure parameters were identical, depending on the area in the joint region observed. In other words, we have obtained an advanced technique for microstructure control that enables us to fabricate peculiar microstructures in limited regions by utilizing FSW or friction stirring in the surface region.
160.
Shibayanagi, T. and M. Maeda (2005). "Microstructure and hardness of friction stir welded 7075 aluminium alloy joints." Welding International 19(6): 425-432.
The main aim of this study is, by applying the friction stir welding (FSW) method to butt welding of A7075 (which is a type of high-tensile aluminium alloy), to analyse the structure of the welded joints obtained by using an optical microscope and the SEM-EBSP (electron back scatter pattern) method so that basic knowledge can be acquired to control the structure of the joint.
161.
Shields, T. C., J. S. Abell, et al. (1995). "Electron Backscatter Diffraction Study of Melt-Processed High-Tc Superconductor YBa2Cu3O7-Delta." Institute of Physics Conference Series 147: 425-428.
162.
Shim, S., H, K. Niihara, et al. (2002). "Crystallographic orientation of ZrB2-ZrC composites manufactured by the spark plasma sintering method." Journal of Microscopy 205(3): 238-244.
The crystallographic grain orientation of ZrB2-ZrC composites manufactured using a spark plasma sintering (SPS) method, a new sintering technique in development for poorly sinterable ceramic materials, was analysed by the scanning electron microscopy-electron backscattered diffraction (SEM-EBSD) method. Their crystallographic features have been compared with those of a conventionally sintered specimen using a pressureless sintering (PLS) method. In the composite sintered by PLS, (0001) planes of ZrB2 were orientated in the direction parallel to the specimen surface (RD) but (1010) and (2110) planes randomly orientated. In the case of SPS, (0001) planes of ZrB2 were orientated normal to the specimen surface (ND) and weakly to the RD. In both cases of PLS and SPS, ZrC grains had a randomly orientated grain structure. The distribution of grain boundary misorientation of PLS and SPS-processed composites showed the same tendency that high-angle boundaries were more prevalent than low-angle boundaries. But in the case of ZrC grains in the SPS sample, the proportion of CSL boundaries with low sigma value (3, 5, 7, 9, 11) was relatively larger.
163.
Shimada, M., H. Kokawa, et al. (2002). "Optimization of grain boundary character distribution for intergranular corrosion resistant 304 stainless steel by twin-induced grain boundary engineering." Acta Materialia 50(9): 2331-2341.
The effects of process parameters, pre-strain, annealing temperature, time, etc. on grain boundary character distribution (GBCD) and intergranular corrosion in thermomechanical treatment were examined during grain boundary engineering of type 304 austenitic stainless steel. Slight pre-strain annealing at a relatively low temperature resulted in excellent intergranular corrosion resistance due to optimized GBCD, i.e. the uniform distribution of a high frequency of coincidence site lattice boundaries and consequent discontinuity of random boundary network in the material. The optimum distribution can be formed by introduction of low energy segments on migrating random boundaries during twin emission and boundary-boundary reactions in the grain growth without generation of new random boundaries.
164.
Shimizu, K. and T. Torii (2002). "The relationship between fatigue properties and microstructures in rolled metal film." JSME International Journal, Series A 45(4): 504-509.
Using two types of specimen that rolling direction was parallel and perpendicular to loading direction in film fatigue testing, effects of rolling texture on fatigue crack propagation properties in iron films of 100 mu m were discussed in relation with the grain size. A crystallographic analysis by EBSD (Electron Backscatter Diffraction) method showed that the anisotropy of rolling texture remained even in the films annealed at 873 K and 1173 K. The cracks in the film with the smaller grain size annealed at 873 K propagated along the grain boundary and the crack propagation rate is approximately the same for both loading direction parallel and perpendicular to the rolling direction. On the other hand, the cracks in the film with the larger grain size annealed at 1173 K propagated across the grain and the crack propagated slower toward the perpendicular direction to the rolling direction than toward the parallel direction. This is probably because the slip system of the rolling texture in a grain of the iron film annealed at 1173 K is different in accordance with the relationship between rolling direction and crack propagation direction. Also, the rolling texture was outstandingly turned around the fatigue crack propagated perpendicular to the rolling direction in the film annealed at 1173 K.
165.
Shimizu, K. and T. Torii (2005). "The effect of microtexture evaluated by electron backscatter diffraction method on fatigue crack propagation behaviour in rolled copper film." Fatigue and Fracture of Engineering Materials and Structures 28(1-2): 221-227.
Using a fatigue-testing method by which a fatigue crack can be propagated in a film adhered to cover an elliptical through-hole in a base plate, annealed rolled copper films have been fatigued. The effects of rolling textures and annealing twin boundaries on fatigue crack propagation behaviour are discussed. The fatigue crack propagates in a large zigzag pattern in the TC specimen (crack perpendicular to the rolling direction), while the crack propagation path in the RC specimen (crack parallel to the rolling direction) is nearly straight. Further, the fatigue cracks propagate slower toward the perpendicular direction than toward the parallel direction. After fatigue testing, the crystallographic characteristic of rolling textures around the fatigue crack in the annealed film is analysed using the EBSD (electron backscatter diffraction) system. Because the annealing twin boundary is in the same plane as the slip of the face-centred-cubic metal, the fatigue crack tends to propagate along the slip line initiated along the annealing twin boundary.
166.
Shimizu, K. and T. Torii (2005). Quantitative evaluation of crystal rotaion behavior around the fatigue crack in copper films. ASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems: Advances in Electronic Packaging 2005, San Francisco, California, USA.
Using a fatigue testing method by which fatigue cracks can be initiated and propagated in a film adhered to cover a circular through-hole in a base plate subjected to pull-pull cyclic loads, annealed rolled pure copper films of 100 µm thickness were fatigued. In order to discuss about the correlation between fatigue crack propagation and the change of crystal orientation, crystal orientation on the surface of the film materials was measured before and after fatigue testing. The crystal lographic information of these films was analyzed using the EBSD (Electron Back-scatter Diffraction) system and the quantitative evaluation method for the crystal rotation angle, the rotation axis and the rotation direction with fatigue testing was developed based on the analysis of crystal orientation matrix, As a result. the crystal rotation angle near the fatigue crack is larger than that apart from the crack and the crystal rotation was quantitatively larger around the transgranular crack than the intergranular crack propagated along the annealing twin boundary.
167.
Shimizu, K., T. Torii, et al. (2004). "Measurement of Crystal Orientation around the Fatigue Crack in Iron Films Using EBSD Method." Journal of the Society of Materials Science, Japan 53(9): 987-993.
Using a fatigue testing method by which fatigue cracks can be initiated and propagated in a film adhered to cover a circular through-hole in a base plate subjected to pull-pull cyclic loads, annealed rolled commercially-pure iron films of 100 mu m thickness were fatigued under constant stress amplitudes with a stress ratio of R=0. In order to discuss correlation between fatigue crack propagation and change of crystal orientation, crystal orientation on the surface of the film materials was measured before and after fatigue testing. The crystallographic information of these films was analyzed using the Electron Back-scatter Diffraction (ESBD) system. As a result, the fatigue crack propagated not only along the boundary of crystal grains but also in a crystal grain and it was found that the scatter of crystal orientation around the fatigue crack on the films became larger after the crack initiation and propagation than before fatigue testing.
168.
Shimizu, K., T. Torii, et al. (2005). "Crystal rotation with fatigue crack propagation in copper films." Journal of the Society of Materials Science, Japan 54(9): 903-908.
The fatigue crack initiation and propagation behaviors were examined for pure copper films of 100 µm thickness. The cold rolled films were annealed and adhered to cover a circular through hole in a base plate. The base plate was subjected to constant cyclic stress with a stress ratio of R = 0. In order to discuss correlation between fatigue crack propagation and change of crystal orientation, crystal orientation on the surface of the copper film was measured before and after fatigue testing. The crystallographic information of these films was analyzed using the electron back-scatter diffraction (EBSD) system and the quantitative evaluation method for the crystal rotation angle and the rotation axis, the rotation direction with fatigue was developed. As a result, the crystal rotation angle near the fatigue crack is larger than that apart from the crack but that is quantitatively small around the crack propagated on the annealing twin boundary.
169.
Shimizu, K., T. Torii, et al. (2005). "Quantitative evaluation method of crystal rotation with fatigue in metal films." Journal of the Society of Materials Science, Japan 54(10): 1041-1046.
The fatigue crack initiation and propagation behaviors were examined for commercially-pure iron films of 100 µm thickness. The cold rolled films were annealed and adhered to cover a circular through hole in a base plate. The base plate was subjected to constant cyclic stress with a stress ratio of R=0. In order to discuss correlation between fatigue crack propagation and change of crystal orientation, crystal orientation on the surface of the film materials was measured before and after fatigue testing. The crystallographic information of these films was analyzed using the electron back-scatter diffraction (EBSD) system and the quantitative evaluation method for the crystal rotation angle and the rotation axis, the rotation direction with fatigue was developed. As a result, the crystal rotation angle near the fatigue crack is larger than that apart from the crack and the crystal rotation was quantitatively larger around the transgranular crack than the intergranular crack.
170.
Shimizu, R., J. Harase, et al. (1990). "Prediction of Secondary Recrystallisation Textures of Fe3%Si." Acta Metallurgica et Materialia: 973-978.
171.
Shin, C. S., J.-H. Ryu, et al. (2002). Orientation Coherence of Rolled and Annealed Aluminum Plate. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Change of spatial orientation distributions is investigated in 95% cold rolled aluminum plates annealed at 300°C temperature for 10, 60, 180, and 300 seconds. Spatial distribution of orientations is measured by electron back scattered diffraction (EBSD) technique, and spatial correlation of orientations is calculated using the two-point orientation coherence function (OCF). The orientational relationship around each main orientation can be found as a function of annealing time. Copper, S and brass components are initially distributed in mixture in thin bands, but as annealing time increases to 300 seconds, S and brass components form distinct bands wider thatn 5 µm along sample normal direction and copper component exists in the brass bands.
172.
Shin, H. J., A. J-K., et al. (2002). Simulation of Ridging of Ferritic Stainless Steel Using Crystal Plasticity Finite Element Method. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The ridging problem in ferritic stainless steel is well known and unsolved for more than two decades. Ferritic stainless steel (FSS) sheets exhibit ridging parallel to the rolling direction when subjected to tension or deep drawing. The origin of ridging has not been clearly explained yet. Most models suggested before are too simplified and underestimate the influence of neighboring grains. In this study, we simulate the ridging phenomenon using the crystal plasticity finite element method (CPFEM). We test the previous models with CPFEM and investigate the relations between orientations and ridging by simulating a more realistic case using EBSD results.
173.
Shin, H.-J., J.-K. An, et al. (2003). "The effect of texture on ridging of ferritic stainless steel." Acta Materialia 51(16): 4693-4706.
Ferritic stainless steel sheets exhibit ridging parallel to the rolling direction when subjected to tension or deep drawing. The origin of ridging behavior has not been clearly explained yet. Many people agree that ridging originates from different plastic anisotropies of grains. In this study, 430 and 409L stainless steels having columnar and equiaxed structures were chosen as initial specimens to elucidate the role of microstructure and composition on ridging. The specimens initially having the columnar structure showed severe ridging and 409L stainless steel showed an inferior surface quality. The existence of band-like colonies of similar orientations was found in the center of the sheets by electron back-scattered diffraction measurement. In addition, the previous models suggested by other researchers were examined quantitatively by the crystal plasticity finite element method. In order to obtain a more realistic ridging simulation, the specimens containing variously oriented colonies in a textured matrix were also considered. The simulated results showed that the lower plastic strain ratio of {001} <110> colonies and different shear deformations of {111 }<110> or {112}<110> colonies resulted in ridging. Copyright 2003 Published by Elsevier Ltd on behalf of Acta Materialia Inc. 32 Refs.
174.
Shin, S. Y., B. Hwang, et al. (2006). "Effects of Microstructure on Charpy Impact Properties of API X70 and X80 Line-pipe Steels." Journal of the Korean Institute of Metals and Materials 44(1): 1-9.
This study is concerned with the effects of microstructure on Charpy V-notch impact properties of high-toughness API X70 and X80 line-pipe steels. Three kinds of steels were fabricated by varying alloying elements and hot-rolling conditions, and their microstructures and Charpy impact properties were investigated. In addition, their effective grain sizes were characterized by the electron back-scatter diffraction (EBSD) analysis. The Charpy impact test results indicated that the steels rolled in the single phase region had the higher upper shelf energy (USE) than the steel rolled in the two phase region because their microstructures were composed of acicular ferrites. In the X80 steel rolled in the single phase region, the decreased energy transition temperature (ETT) could be explained by the decrease in the overall effective grain size due to the presence of acicular ferrite having smaller effective grain size. Thus, it had excellent mechanical properties including high yield and tensile strengths, high USE, and low ETT, although its elongation was low.
175.
Shin, S.-D., D.-Y. Kim, et al. (2005). "Crystal growth in the low-temperature deposition of polycrystalline silicon thin film." Journal of Crystal Growth 274(3-4): 347-354.
In this study, the microstructure and property of poly-Si film, deposited using hot wire chemical vapor deposition (HWCVD) were investigated. A consequence of the low a-Si content in the poly-Si film was crystallites with well developed facets. The crystallite morphology was rhombic pyramidal while EBSD analysis revealed the existence of (1 1 1) contact twin planes. The facets of the rhombic pyramidal crystallites were based on {320} and {320 }* planes, which have Σ3 twin relationship with respect to (1 1 1) contact twin plane. Copyright 2004 Published by Elsevier B.V.
176.
Shin, T.-J., J.-O. Oh, et al. (2004). "The mechanism of abnormal grain growth in polycrystalline diamond during high pressure-high temperature sintering." Diamond and Related Materials 13(3): 488-494.
The abnormal grain growth (AGG) in polycrystalline diamond (PCD) during high pressure-high temperature sintering (6 GPa; 1600 degrees C) was investigated. Some grains grew to a size of several hundreds of micrometers in PCD manufactured with 2- mu m diamond powder. However, the AGG distribution was inhomogeneous possibly due to the inhomogeneous pressure distribution. When the initial average particle diameter of diamond powder was 4 µm. no AGG was observed within the experimental range (1 h) due to an increase in the diffusion distance. Electron backscattered diffraction technique was used to show that the abnormally grown grains were single crystals with and without their twins with the {111} twinning planes. The {111} faceted planes developed in the abnormally grown crystals, suggesting that AGG in PCD could be explained by the 2D nucleation mechanism.
177.
Shvindlerman, L. S. and B. B. Straumal (1985). "Regions of Existence of Special and Non-Special Grain-Boundaries." Acta Metallurgica 33(9): 1735-1749.
178.
Sil, D. and S. K. Varma (1993). "The Combined Effect of Grain-Size and Strain-Rate on the Dislocation Substructures and Mechanical-Properties in Pure Aluminum." Metallurgical Transactions A 24(5): 1153-1161.
179.
Silva, F., N. I. A. Lopes, et al. (2006). "Microstructural characterization of the C-Mn multiphase high strength cold rolled steel." Materials Characterization 56(1): 19-25.
The multiphase steels have microstructures containing, ferrite, martensite, bainite, carbide particles and a small amount of retained austenite. This microstructure, according to the volume fraction of each constituent, provides the steel with a high mechanical strength and good ductility. Different thermal cycles were simulated in the laboratory to attempt to create microstructures with improved mechanical properties. The samples were heated to 750 °C for 300 s, and then quickly cooled to 500 °C, soaked for another 300 s and then submitted to the accelerated cooling process, with rates of 2–100 °C/s. The microstructure was examined at the end of each different thermal cycle. The mechanical behavior evaluation was made by microindentation hardness testing. The microstructural characterization involved Optical Microscopy (OM), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and the identification of phases was made using the Electron Backscatter Diffraction technique (EBSD).
180.
Silva, M. D. C. A. D. L., Fernando Jose Gomes; Falleiros, Ivan Gilberto Sandoval (2004). Evolution of Deformation Texture of the GNO With 1.25% Si Electric Steel. 59 deg Congresso Anual da Associacao Brasileira de Metalurgia e Materiais: 59th Annual ABM International Congress, Sao Paulo, Brazil, Associacao Brasileira de Metalurgia e Materiais.
An oriented grain electric steel with 1.25 wt % was cold rolled varying reduction degree in thickness from 10 to 90%. In this paper the texture evolution with deformation degree is observed. The deformation texture is related to the recrystallization texture, which affects in magnetic properties. Samples were characterized by MEV equipped with EBSD, optical microscopy and hardness measurements. Subdivided grain, abrupt changes orientation are easily seen since 10% reduction. For reduction 40% deformation lines were observed. The were observed by optical microscopyon sample reduced 70% or more. After 20% reduction fiber preferred orientation was observed alpha {hkl} < 110 > e gamma 111 < uvw >, which are typical textures of cold rolled.
181.
Simkin, B. A., B. C. Ng, et al. (2003). "Orientation determination and defect analysis in the near-cubic intermetallic gamma -TiAl using SACP, ECCI, and EBSD." Intermetallics 11(3): 215-223.
Crystal orientation and defect analysis for the commercially important gamma -TiAl intermetallic compound is complicated by the near-cubic tetragonality of the L10 TiAl crystal structure. The selected area channeling pattern (SACP) method successfully reveals the gamma -TiAl superlattice information, allowing accurate discrimination between the c and a directions that are commonly unattainable by the conventional electron backscattered diffraction (EBSD) method. Combination of this orientation information with crystal defect images obtained via the electron channeling contrast imaging (ECCI) method allows for rapid identification of active deformation systems in individual grains using a trace analysis scheme. Because SACP and ECCI are scanning electron microscopy (SEM) based techniques, analysis can be carried out on regularly shaped macroscopic samples, allowing association of the sample stress state and active defect systems. This has been shown in relation to defect analysis associated with strain transfer at grain boundaries. Additionally, the orientations determined via SACP have been used to correct EBSD data in order to reveal localized rotation due to retained strain within individual grains.
182.
Simkin, B. A., T. R. Bieler, et al. (1999). The effect of texture on microyielding in near-gamma Ti-Al alloys. ICOTOM 12 - Twelfth International Conference on Textures of Materials, McGill University, Montreal, Canada, NRC Research Press.
183.
Simons, G., K. Kunze, et al. (2004). Three-dimensional microstructure of thin copper foils revealed by ion beam cutting and electron backscatter diffraction (EBSD). 2nd International Conference on Texture and Anisotropy of Polycrystals (ITAP 2), Metz, France, Balaban Publishers; Scitec Publications.
Tensile testing of thin rolled copper foils with thickness ranging from 10 to 250 mu m shows a dependence of the fracture strain with respect to the thickness of the foils. To understand the influence of the microstructure in the foils on this phenomenon the microtexture is investigated by orientation mapping through electron backscatter diffraction (EBSD). As the samples are rather small standard preparation techniques do not apply. Two methods are described which allow the investigation of different section cuts of the samples: Cross sections of the samples were produced by ion beam cutting with a wide beam of 7 keV Kr ions. Internal planes parallel to the specimen surface were made accessible by wet etching. The as-received material possesses a very strong texture consisting mostly of the cube component and some remnants of a previous rolling texture. Specimens tested in a tensile test do not show major microstructural changes compared to virgin samples. After a heat treatment at 300 degrees C the cube texture has significantly weakened in favour of revived rolling components, and the fracture strain increased about ten times relative to the as-is material.
184.
Sinclair, C. W. and J.-D. Mithieux (2004). Coupling Recrystallization and Texture to the Mechanical Properties of Ferritic Stainless Steel Sheet. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
185.
Sinclair, C. W., D. Weygand, et al. (2004). Simulating the Topology of Recrystallization in Stabilized Ferritic Stainless Steels. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
186.
Sinclair, C. W., F. Robaut, et al. (2003). "Recrystallization and Texture in a Ferritic Stainless Steel: an EBSD Study." Advanced Engineering Materials 5(8): 570-574.
The recrystallization behavior of laboratory-processed AISI409 ferritic stainless steel sheet has been studied with a focus on texture inhomogeneity and "sluggish" recrystallization kinetics. This communication focuses primarily on observations made by electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM). Pronounced texture gradients were observed in some grain orientations and correlated with the deformation-induced substructure. The strong pinning of some boundaries has been linked, not only to textural effects, but also to the precipitation of fine titanium carbonitrides. Control of plastic anisotropy via the bulk texture of the final product is crucial in this regard and consequently has been heavily studied, particularly for carbon steels. While ferritic stainless steels have a number of similarities to their chromium-free counterparts, the differences in chemistry and therefore processing conditions give rise to a number of important differences. Compared with carbon steels, much less time has been devoted to understanding the relationship between processing, texture, and formability of ferritic stainless steel.
187.
Sinclair, C. W., J.-D. Mithieux, et al. (2005). "Recrystallization of Stabilized Ferritic Stainless Steel Sheet." Metallurgical and Materials Transactions A 36A(11): 3205-3215.
An experimental study of the microstructural evolution attending recrystallization of cold-rolled Ti-stabilized ferritic stainless steel is presented. Particular attention is paid to the slow approach to full recrystallization. It is shown that this "sluggish" recrystallization can be attributed to the heterogeneity of microstructure and texture resulting from the processing of the material. In particular, it is shown that the presence of fine Ti(C,N) precipitates acts to significantly hinder the final approach to full recrystallization.
188.
Sinha, V., J. E. Spowart, et al. (2006). "Observations on the faceted initiation site in the dwell-fatigue tested Ti-6242 alloy: Crystallographic orientation and size effects." Metallurgical and Materials Transactions A 37(5): 1507-1518.
A novel use of the electron backscattered diffraction (EBSD) characterization technique for study of fracture has been demonstrated. This new approach has been employed for characterization and analysis that contribute to the understanding of crack initiation in Ti-6242 under dwell-fatigue loading conditions. A faceted crack initiation site is typically observed on the dwell-fatigue fracture surface of Ti-6242. The level of microtexture has a major influence on the dwell-fatigue failures in near-α titanium alloys, such as Ti-6242. In this study, serial sectioning and EBSD techniques were used to obtain the orientation images of almost the entire specimen cross section at different depths below the fracture surface. The orientation images are color coded on three different bases: the angle between the loading axis and basal plane normal, the Schmid factor for prism slip, and the Schmid factor for basal slip. The aim was to determine the important aspects of the crystallographic orientation and the size of the microtextured region that is associated with the faceted initiation site. The results of this study are used to explain the possible locations of crack initiation in a test specimen under dwell-fatigue loading condition. These results are also used to better understand the role of size of microtextured regions in determining which crack will outgrow the other cracks (for the case of multiple cracking typically observed in the alloy of current study under the dwell-fatigue loading conditions) to become the dominant crack that leads to eventual specimen failure. This understanding has important practical implications because the dominant crack effectively determines the specimen life.
189.
Sitdikov, O., T. Sakai, et al. (2004). New Grain Formation in a Coarse-Grained 7475 Al Alloy during Severe Hot Forging. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
Strain-induced grain refinement in a goarse-grained 7475Al alloy was studied by means of multidirectional forging (MDF) carried out at T=490°C under a strain rate of 3 x 10-4s-1. Integrated flow curves exhibit significant work softening just after yielding, followed by steady-state-like behavior at high strains. The evolution of new fine grain structure during deformation can be assisted by grain-boundary sliding, resulting in frequent formation of high strain gradients and subsequently microshear bands in grain interiors. Microshear bands developed in various directions are intersected with each other, subdividing original grains into misoriented small domains. The number and the misorienatation angle of microshear bands progressively increase during deformation, finally followed by their transformation into high-angle boundaries. It is concluded that grain refinement under hot MDF conditions occurs by a series of deformation-induced continuous reactions; that is essentially similar to continuous dynamic recrystallization.
190.
Sitzman, S. D. (2004). Introduction to EBSD analysis of micro- to nanoscale microstructures in metals and ceramics. Testing, Reliability, and Application of Micro and Nano-Material Systems II, San Diego, California, USA, SPIE International Society for Optical Engineering.
Electron BackScatter Diffraction (EBSD) is a relatively new, scanning electron microscope-based technique used to characterize microstructures and textures in crystalline metal and ceramic materials. Advances in SEM technology, especially the development of field emission SEMs, as well as in EBSD detector design have allowed characterization at the sub-10 nm level. This paper gives a basic introduction to the EBSD technique with applications on materials with microstructures on the micron and sub-micron scale. Automated EBSD mapping at these and other resolution levels is used to study texture, individual grain orientation, crystallography-based phase identification, grain size, grain shape, strain state, grain boundary character, area percentages of multiple phases in bulk samples, crystallography of facets and failure initiation sites, and other materials characteristics. Sample sectioning and polishing are often necessary for mapping microstructures in bulk samples, however as-grown structures such as thin films and interconnects are suitable for mapping as is, and "point & shoot" type analyses may be used on other unprepared samples in conjunction with SEM imaging for phase identification and basic crystallographic orientation studies. For micron-scale devices and components, EBSD-equipped dual beam FIBs are used to select cross-sectional planes of analysis with high precision.
191.
Sivakumar, G., M. Naveen, et al. (2004). Comparison of Detonation and Plasma Sprayed Low Alloy Steel Coatings for Possible Automotive Cylinder Bore Applications. 59th Annual Technical Meeting of the Indian Institute of Metals, India, Chennai, Indian Institute of Metals.
The present study deals with a comprehensive evaluation of coatings formed by detonation and plasma spraying of a low alloy steel powder (Fe-0.2C-0.5Mn) under varying processing conditions. Detailed evaluation of all coated specimens for microstructure, phase constitution and hardness was carried out. EBSD and nanoindentation studies were also performed.
192.
Sivel, V. G. M., F. D. Tichelaar, et al. (2005). "Crystallographic analysis of thin specimens." Journal of Microscopy 218(Pt. 2): 115-124.
Electron backscattering diffraction (EBSD) is commonly used on bulk samples for crystallographic material characterization. In this work, the technique was applied on transmission electron microscopy (TEM)-type thin specimens, prepared with a focused ion beam. Orientation maps were successfully collected on specimens made of a Cu3Au coppergold alloy. As compared to EBSD analysis on a bulk specimen, an improved pattern quality and a high spatial resolution (well below 10 nm) were obtained. Furthermore, a clear improvement of the signal-to-noise ratio with decreasing sample thickness was observed.
193.
Sivel, V. G. M., P. F. A.Alkemade, et al. (2004). EBSD on lift out specimens. European Microscopy Congress 2004, Antwerp, Belgium.
194.
Skidmore, T., R. G. Buchheit, et al. (2004). "Grain boundary energy vs. misorientation in Inconel 600 alloy as measured by thermal groove and OIM analysis correlation." Scripta Materialia 50: 873-877.
Samples of Inconel 600 foil were annealed to form a bamboo structure with grain boundary grooves. Grain boundary misorientation was measured using OIM and groove root angle was measured by AFM. Analysis of the data showed a misorientation vs. grain boundary plot that agrees with literature trends for FCC materials.
195.
Skjervold, S. R. and N. Ryum (1995). "Characterization of Local Texture in a Moderately Deformed Polycrystalline AlSi-Alloy." Acta Metallurgica et Materialia 43(8): 3159-3176.
196.
Skjervold, S. R. and N. Ryum (1996). "Orientation Relationships in a Partially Recrystallized Polycrystalline AlSi-Alloy." Acta Materialia 44(8): 3407-3419.
A moderately deformed polycrystalline AlSi alloy of initially random texture whose deformation structure is discussed in an accompanying paper was annealed until partial recrystallisation. The nucleation of recrystallised grains occurred preferentially in regions of large misorientation gradients. Particularly potent regions were shown to be the grain boundary and triple line regions, and the regions close to individual second phase particles or clusters of such particles. It was found that a majority of the recrystallised grains were developed in regions where a cumulative rotation of the lattice about a <111>-axis occurred. The angle of rotation about a <111>-axis of grains relative to the surrounding matrix was in the range 35–45° for about 50% of these cases. The preferred selection of recrystallised grains having the ~40° <111> orientation relationship is suggested to be due to the easy formation of such sites in the deformed matrix and also to their preferential growth potential—compromise between the frequency of available nuclei and their respective growth velocities.
197.
Skrotzki, W., H. Wendt, et al. (1988). "The Relation Between the Structure and Mechanical-Properties of a Sigma=51 Tilt Boundary in Germanium." Acta Metallurgica 36(4): 983-994.
198.
Skrotzki, W., I. Hünsche, et al. (2004). "Substructure and texture formation during extrusion of NiAl single crystals." Materials Science and Engineering A 387-389: 981-984.
<1 0 0> and <1 1 0> oriented NiAl single crystals have been extruded at 1000 °C through a round die. The crystals subdivide into two types of deformation bands producing fibre texture components parallel and normal to the extrusion axis. These rotations as well as shape changes under partially constrained deformation conditions yield informations on the slip system activity. The relevance of deformation banding on texture formation in polycrystals is discussed.
199.
Skrotzki, W., K. Kegler, et al. (2004). Recrystallization of Iron Aluminides. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
200.
Skrotzki, W., K. Kegler, et al. (2005). "Grain structure and texture of cast iron aluminides." Crystal Research and Technology 40(1-2): 90-94.
The grain structure and texture of cast iron aluminides have been investigated in the scanning electron microscope by orientation contrast imaging and electron back-scatter diffraction, respectively. Depending on the aluminum concentration the alloys exhibit a fine-grained chill zone, medium grain size columnar zone and/or coarse-grained equiaxed zone. The texture is random except in the columnar zone which is characterized by a < 100 > fibre texture in the direction of heat flow, i.e parallel to the elongated grains. The development of grain structure and texture is discussed with respect to cooling rate, thermal and constitutional undercooling, and order.
201.
Skrotzki, W., M. Lemke, et al. (1997). "Development of Microstructure and Texture in Extruded NiAl." Materials Science and Engineering A 234-236: 739-742.
202.
Skrotzki, W., N. Scheerbaum, et al. (2004). Oblique cube texture formation in high purity aluminum during equal channel angular pressing. 2nd International Conference on Texture and Anisotropy of Polycrystals (ITAP 2), Metz, France, Balaban Publishers; Scitec Publications.
Aluminum of 5N purity has been deformed at room temperature by equal channel angular pressing using three passes of route A. The microstructure and texture have been investigated by electron back-scattering and neutron diffraction. The microstructure from the first pass on is totally dynamically recrystallized. The recrystallization texture consists of an oblique cube component. The oblate grains and the cube texture are anticlockwise rotated about the transverse direction. The inclination with respect to the extrusion direction depends on the distance from the top of the extruded bar and changes from pass to pass. The mechanism of formation of the recrystallization microstructure and texture is discussed.
203.
Skrotzki, W., N. Scheerbaum, et al. (2004). Texture gradient in ECAP copper measured by synchrotron radiation. 2nd International Conference on Texture and Anisotropy of Polycrystals (ITAP 2), Metz, France, Balaban Publishers; Scitec Publications.
Copper of 4N purity was deformed at room temperature by equal channel angular pressing (ECAP) using three passes of route A. The local microstructure and texture were investigated by orientation imaging microscopy and high-energy synchrotron radiation, respectively. The microstructure consists of elongated grains which are inclined to the extrusion direction. The texture is characterized by typical shear components of fcc metals which deviate from their ideal positions. The inclination of the grain long axis and the texture components with respect to the extrusion direction depends on the distance from the top of the extruded bar and changes from pass to pass. Reasons for the texture gradient are discussed.
204.
Skrotzki, W., R. Tamm, et al. (1999). On the texture change in extruded NiAl. Twelfth International Conference on Textures of Materials (ICOTOM 12), McGill University, Montreal, Canada, NRC Research Press.
205.
Skrotzki, W., R. Tamm, et al. (2000). "Microstructure and texture formationin extruded lead sulfide (galena)." Journal of Structural Geology 22(No. 1): 1621-32.
206.
Skrotzki, W., R. Tamm, et al. (2000). Effects of Thermomechanical Processing on the Texture and Mechanical Properties of NiAl. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
The textures of extruded stoichiometric NiAl have been measured by neutron and electron diffraction. The type of texture depends on the extrusion geometry and temperature. Extrusion through a round and rectangular die leads to a <110> fibre and a predominant {111 }<110> component deformation texture, respectively. The texture changes to a <111> fibre and a {110}<110> component by dynamic as well as static recrystallization. The kinetics of recrystallization and grain growth are discussed. The strength of the samples depends on the preferred orientation with respect to the compression axis, with <100> being much harder than those with <110> and <111>.
207.
Skrotzki, W., R. Tamm, et al. (2003). Effects of Thermomechanical Processing on Texture Formation in Iron Aluminides. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
Iron aluminide of different compositions have been deformed at high temperatures by extrusion through a round and rectangular die, approximating tension and plane strain deformation, respectively. Depending on temperature and composition, recrystallization takes place. Global and local textures have been measured by neutron and electron backscatter diffraction (EBSD), respectively. The EBSD allows the separation of deformation and recrystallization texture components. The development of the deformation textures is simulated with the relaxed constraints Taylor model. Moreover, the texture development is correlated with the microstructural evolution derived from EBSD mappings. Conclusions concerning the anisotropy of the elastic and plastic properties are drawn.
208.
Slamova, M., M. Karlik, et al. (2002). "Differences in microstructure and texture of Al-Mg sheets produced by twin-roll continuous casting and by direct-chill casting." Materials Characterization 41(3): 231-240.
Over the last two decades, the use of aluminum sheets in automotive applications has increased. Aluminum sheets are currently produced from direct-chill (DC) cast plates. The need for low-cost aluminum sheets is a challenge for the development of new materials produced by twin-roll continuous (TRC) casting and cold rolling. It is expected that the sheets produced from these different casting procedures can differ in their microstructure. Therefore, they can exhibit different formability behavior. The paper presents the results of the microstructural characterization and texture evaluation of aluminum sheets produced by both technologies. Sheets produced from twin-roll cast materials have much finer and more numerous second-phase particles, the grain structures of both types of materials are similar. Electron backscatter diffraction (EBSD) and X-ray diffraction techniques were used for texture evaluation and both confirmed the presence of stronger cube texture in the strips produced from DC-cast plates.
209.
Slangen, M. H. J., D. Reefman, et al. (1996). Electron Backscatter Diffraction as a Tool to Study the Microtexture of Tungsten Filaments. Eleventh International Conference on Textures of Materials, Xi'an, China, International Academic Publishers.
210.
Slavik, D. C. (1994). Identifying fracture mechanisms with the EBSP technique. Fifty-Second Annual Meeting Microscopy Society of America/Twenty-Ninth Annual Meeting Microbeam Analysis Society, New Orleans, LA, San Fancisco Press, Inc.
Stress corrosion cracking (SCC), liquid metal embrittlement, and corrosion fatigue cracking mechanisms can be evaluated by measuring grain boundary misorientations along the crack path or the crystallography of fracture surface facets. The crystallographic orientation of individual grains can be measured with a variety of techniques including electron back scatter pattern (EBSP) techniques. EBSPs are unique since a large statistical sampling of individual grains or subgrains as small as a micrometer in diameter can be probed on single large samples. [References: 4]
211.
Slavik, D. C. and R. P. Gangloff (1996). "Environment and Microstructure Effects on Fatigue-Crack Facet Orientation in an Al-Li-Cu-Zr Alloy." Acta Materialia 44(9): 3515-3534.
The effects of environment, microstructure and texture on transgranular fatigue crack facet orientation are established with electron-back scattered pattern analysis and stereofractography for single grains in peak aged Al---Li---Cu---Zr alloy 2090. For vacuum, facets are near-{111} due to fatigue fracture through intense deformation bands with a complex planar-slip dislocation structure. Multiple facets in single grains and the tortuous crack path are caused by high shear stresses resolved on multiple slip systems. Low stress intensity range fatigue fracture in NaCl is transgranular and faceted, but not tortuous. Eighty-five per cent of the facets in unrecrystallized plate and 50% of the facets in recrystallized sheet are within 10° of a high index plane, on average {521}, subjected to high normal stresses. Such facets are inconsistent with: (a) hydrogen-enhanced localized plasticity and {111} decohesion; (b) slip-locking with bisecting {100} cracking; (c) environment-enhanced alternate slip with {100} faceting; or (d) {100}/{100} decohesion. Environmental fatigue may be governed by faceted cracking associated with hydrides or hydrogen embrittled dislocation cell walls.
212.
Slavik, D. C., J. A. Wert, et al. (1993). "Determining fracture facet crystallography using electron backscatter patterns and quantitative tilt fractography." Journal of Materials Research 8(10): 2482-2491.
A methodology is presented to characterize the crystallography of individual fracture surface facets. Electron backscatter patterns (EBSP's) from a metallographic section through a facet identify grain orientation, and quantitative tilt fractography identifies facet orientation; these results are combined to establish fracture facet crystallography. For this technique, facet electropolishing is not required, the facet alignment procedure is accurate and quick, and the method can be generalized to different microstructures, test environments, or facet orientations. Method accuracy is illustrated for 25 to 50 mu m fatigue crack facets in an unrecrystallized Al-Li-Cu alloy (AA2090) that has 5 mu m thick subgrains in elongated grains that are 10 to 200 mu m thick. The fine subgrain structure and tortuous fatigue crack profile precludes the use of other diffraction techniques for determining AA2090 facet crystallography. EBSP and tilt fractography results demonstrate that vacuum fatigue cracks in AA2090 are nearly parallel to local left brace 111 right brace planes. (Author abstract) [References: 31]
213.
Slotemaker, A. K., J. H. P. d. Bresser, et al. (2004). Microstructural Evolution of Synthetic Forsterite Aggregates Deformed to High Strain. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
214.
Small, A., J. R. Michael, et al. (2002). "Improving the quality of electron backscatter diffraction (EBSD) patterns from nanoparticles." Journal of Microscopy 206(2): 170.
In this study, we investigated the relative contributions of atomic number (Z) and density (ρ) to the degradation of the electron backscatter diffraction (EBSD) pattern quality for nanoparticles < 500 nm in diameter. This was accomplished by minimizing the diffuse scattering from the conventional thick mounting substrate through the design of a sample holder that can accommodate particles mounted on thin-film TEM substrates. With this design, the contributions of incoherently scattered electrons that result in the diffuse background are minimized. Qualitative and quantitative comparisons were made of the EBSD pattern quality obtained from Al2O3 particles approximately 200 nm in diameter mounted on both thick- and thin-film C substrates. For the quantitative comparison we developed a ‘quality’ factor for EBSD patterns that is based on the ratio of two Hough transforms derived from a given EBSD pattern image. The calculated quality factor is directly proportional to the signal- to-noise ratio for the EBSD pattern. In addition to the comparison of the thick and thin mounting substrates, we also estimated the effects of Z and ρ by comparing the EBSD pattern quality from the Al2O3 particles mounted on thin-film substrates with the quality of patterns obtained from Fe–Co nanoparticles approximately 120 nm in diameter. The results indicate that the increased background generated in EBSD patterns by the electrons escaping through the bottom of the small particles is the dominant reason for the poor EBSD pattern quality from nanoparticles < 500 nm in size. This was supported by the fact that we were able to obtain usable EBSD patterns from Al2O3 particles as small as 130 nm using the thin-film mounting method.
215.
Small, J. A. and J. Michael (2001). "Phase identification of individual crystalline particles by electron backscatter diffraction." Journal of Microscopy 201(Pt. 1): 59-69.
Recently, an electron backscatter diffraction (EBSD) system was developed that uses a 1024 x 1024 CCD camera coupled to a thin phosphor. This camera has been shown to produce excellent EBSD patterns. In this system, crystallographic information is determined from the EBSD pattern and coupled with the elemental information from energy or wavelength dispersive X-ray spectrometry. Identification of the crystalline phase of a sample is then made through a link to a commercial diffraction database. To date, this system has been applied almost exclusively to conventional, bulk samples that have been polished to a flat surface. In this investigation, we report on the application of the EBSD system to the phase identification analysis of individual micrometre and submicrometre particles rather than flat surfaces.
216.
Small, J. and J. R. Michael (1999). Phase Identification of Individual Particles by Electron Backscatter Diffraction (EBSD). Microscopy and Microanalysis, Portland, Oregon, Springer-Verlag.
217.
Smalley, A. L. E. (2005). Synthesis, crystal chemistry, and properties of skutterudites, University of Oregon. Ph.D.: 113.
Skutterudites are a class of materials that have been studied for a number of years, and are considered to be promising for thermoelectric applications. Previous research has shown that it is possible to synthesize metastable skutterudites using low-temperature synthetic methods. In this dissertation we examine the extended compositional ranges over which several skutterudites will form using the ultra-thin layer, elemental deposition method, and explore the effects of composition on the material's properties. We have found that the amount of filler atoms in filled skutterudites, the range of possible metal to pnictide ratios, and how the properties respond depend on the system. For example, Co-rich samples of CoSb3 were n-type, and the number of charge carriers decreased with annealing. Samples that had the ideal stoichiometry were n-type, but the charge carriers were relatively stable. Sb-rich samples started n-type, and became p-type with annealing. This indicates how sensitive the properties are to changes in composition.We have also discovered the presence of secondary phases in samples that appear single phase when analyzed using X-ray diffraction. We used Rietveld refinement and quantitative analysis on the samples to determine the percent crystallinity. Some of them were only 5% crystalline, whereas others were nearly 100% crystalline, depending on the system and the composition. The amount of crystallinity was larger in the more stable samples and smaller in the less stable ones. We used several methods to confirm the crystallinity and the presence of secondary phases. In the case of the CexCo4Sb12 samples, magnetic measurements confirmed the presence of a secondary phase that contributed a ferromagnetic signal. Mössbauer spectroscopy on the FeSb3 samples revealed that the majority phase had the chemical environment of FeSb2. Finally, we used electron back-scatter diffraction to image these samples and gain insight into the mechanism by which they crystallize. EBSD data indicated that the growing grains exclude elements that are not soluble in the crystal. We presume that crystal growth stops because the grain boundaries have become depleted in the elements required to allow continued growth in the crystal grains.
218.
Smith, D. A. (1982). "Interaction of Dislocations with Grain-Boundaries." Journal de Physique I 43(NC-6): 225-237.
219.
Smith, D. A. (1989). "Grain-Boundary Structure and Migration." Ultramicroscopy 29(1-4): 1-8.
220.
Smith, D. A. (1992). "From Single Defects to a Structure Property Relationship for Polycrystals." Ultramicroscopy 40(3): 321-329.
221.
Smith, D. A. and C. S. Nichols (1993). "Aggregates and Grain-Boundaries - Structure and Properties." Materials Science and Engineering A 166(1-2): 29-34.
222.
Snyder, W. E., H. Qi, et al. "A coordinate system for hexagonal pixels."
A coordinate system is described which provides a natural means for representing hexagonally-organized pixels. The coordinate system has the unusual property that its basis vectors are not orthogonal. Vector-space properties and operations are described in this coordinate system, and shown to be straightforward computations. Some image processing algorithms, including calculations of image gradients and variable-conductance diffusion, are expressed and analyzed.
223.
Solenthaler, C. (1990). "On Dislocation Reactions in FCC-Sigma-3 Twin Boundaries." Materials Science and Engineering A 125(1): 57-66.
224.
Sommitsch, C. and W. Mitter (2006). "On modelling of dynamic recrystallisation of fcc materials with low stacking fault energy." Acta Materialia 54: 357-375.
A model for dynamic recrystallisation is presented, which was developed for face-centred cubic materials with low stacking fault energies. The critical conditions for nucleation are derived and a nucleation model is used that defines the nucleation rate as the velocity determining factor and that is based on the thermal climb of edge dislocations. Stable nuclei grow in dependence on the grain boundary mobility, thus a grain size distribution can be derived. During deformation, a time- dependent dislocation density gradient develops in the recrystallised grains, which leads to a corresponding dislocation density over all recrystallised grains. If the recrystallised grain fraction meets the critical conditions for the onset of recrystallisation, a second cycle will start. The development of grain size and recrystallised fraction is compared with measured data.
225.
Sommitsch, C., M. Walter, et al. (2003). Modeling and Investigation of Dynamic Recrystallization in Nickel-Based Superalloys. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
A process model for the calculation of the microstructure evolution of nickel-based alloys during a hot forming process helps to optimize the forming process and to achieve the desired microstructure. In the grain structure model, the mean dislocation density rate within a homogeneous area can be estimated by the summation of a work hardening and a recovery rate. If a critical dislocation density is reached, recrystallization nuclei will form. This critical dislocation density and the correspondent critical nucleus size can be calculated with a nucleation criterion for dynamic recrystallization. During dynamic recrystallization the nucleation process takes place at the grain boundaries of the deformed grains. The number of grains as a function of time is described by both a phenomenological and a physical based approach. The model was tested by a comprehensive experimental program with the alloy 80A.
226.
Song, J. M., L. H. Chen, et al. (2003). "Examination on the growth textures of eutectic cementite of various morphologies." Materials Science and Engineering A A347(1-2): 5-8.
The microtexture of eutectic cementite with various morphologies was determined by using electron back-scattered diffraction (EBSD). Experimental results showed a higher carbon content and directional solidification lead to straight interfaces of the cementite. And the eutectic cementite with straight interfaces possesses a preferred Ý001¨c growth direction due to the edge-wise growth; on the contrary, cementite with curved interfaces has a more random texture resulting from cooperative growth.
227.
Song, J. M., T. S. Lui, et al. (2002). "A Study on Inhomogeneous Distribution of Temper Graphite Particles in Strip-Cast Fe-C-Si Alloys." Metallurgical and Materials Transactions A 33(April): 1263-1273.
This study examined the relationship between solidification structure and graphitization characteristics of white cast iron strips produced by strip casting. Experimental results showed that there was an unususl distribution of temper graphite particles along the through-thickness direction of the graphitized strips in comparison with gravity-cast chill plate. In particular, the graphite-free zones appeared in the vicinity of the strip surface after the completion of graphitization, especially in the strip with low carbon and silicon content. There were abnormally straight interfaces between matrix and eutectic cementite with a strong preferred [001]c growth direction caused by the effect of directional solidification found in the near-surface regions of the strips. The interfaces did not form a site for the graphite to nucleate and gave rise to the graphite-free zones close to the strip surface. An increase in carbon and silicon content could significantly increase the number of temper graphite particles and shorten the time for the completion of graphitization, but an inhomogenous distribution feature of graphite particles was still observed in strips with a higher carbon equivalent value (CE). Furthermore, variations in carbon and silicon content resulted in transitions in carbide morphology and composition, which had a tremendous effect on the graphitization characteristics of the cast iron strips.
228.
Song, R., D. Ponge, et al. (2005). "Microstructure and crystallographic texture of an ultrafine grained C–Mn steel and their evolution during warm deformation and annealing." Acta Materialia 53: 845-858.
The evolution of microstructure and texture of a 0.2%C–Mn steel during large strain warm deformation and subsequent annealing has been investigated. The process of grain subdivision during warm deformation is essential for the formation of ultrafine grains in such a material. The study reveals that pronounced recovery instead of primary recrystallization is required to obtain a large fraction of high-angle grain boundaries (HAGBs) as a prerequisite for the development of ultrafine grains in the course of warm deformation. The prevalence of primary recrystallization instead of recovery is not generally beneficial in this context since it reduces significantly the dislocation density and removes the substructure which is important for the gradual formation of subgrains and, finally, of ultrafine grains which are surrounded by HAGBs. Consistently, the texture of the ultrafine grained 0.2%C–Mn steel observed after large strain warm deformation and subsequent annealing, consists primarily of the α-(<1 1 0>||RD) texture fiber which indicates strong recovery. The γ-(<1 1 1>||ND) texture fiber which is typical of recrystallized rolled ferritic steels does not appear. The process occurring during the deformation and subsequent annealing can, therefore, be interpreted as a pronounced recovery process during which new grains are created without preceding nucleation.
229.
Soubeyroux, J. L., C. E. Bruzek, et al. (2005). "Thermal treatments for biaxially textured Cu-Ni alloys for YBCO coated conductors." IEEE Transactions on Applied Superconductivity 15(2): 2687-2690.
We have studied the thermal treatments necessary to texture Cu-Ni alloys in view of applications as substrate for the YBCO coated conductors. Several alloy compositions chosen in order to avoid magnetism of the tapes have been elaborated by the rolling (RABiTS) method. Analyzes of the texture as a function of annealing temperature have been done by X-ray and neutron diffractions, pole figures by EBSD and X-rays. The results show that the annealing temperature is dependant of the alloy composition and must be determined precisely for each composition. Good biaxial textures have been obtained on these cheap alloys.
230.
Spanos, G. and M. G. Hall (1996). "The formation mechanism(s), morphology, and crystallography of ferrite sideplates." Metallurgical and Materials Transactions A 27(6): 1519-1534.
The formation mechanism(s), morphology, and crystallography of secondary ferrite sideplates were investigated with transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron backscatter pattern (EBSP) analysis, and optical microscopy in a high-purity Fe-0.12 wt pct C-3.3 wt pct Ni alloy isothermally transformed at temperatures of 550 degrees C, 600 degrees C, 650 degrees C, and 675 degrees C. The results indicate that two different mechanisms contribute to the formation of these sideplates at austenite grain boundaries. On the first mechanism, primary sideplates form initially, followed by rapid lateral impingement along their bases, resulting in a region along the grain boundary which very early in the growth process resembles an allotriomorphic film. On the second mechanism, sympathetic nucleation of ferrite sideplates occurs atop pre-existing ferrite allotriomorphs, resulting in ferrite:ferrite grain boundaries and significant crystallographic misorientations between the sideplates and the allotriomorphs with which they are associated. These results indicate that "secondary sideplates" and the allotriomorphs from which they evolve are not composed of monolithic single crystals formed by a morphological instability mechanism but are instead composed of multiple crystals formed by individual nucleation events. Previous investigations in Ti-Cr alloys and a high chromium stainless steel suggest that the findings presented here may be applicable to a number of other alloy systems as well. (44 References).
231.
Spanos, G., A. W. Wilson, et al. (2005). "New Insights into the Widmänstatten Proeutectoid Ferrite Transformation: Integration of Crystallographic and Three-Dimensional Morphological Observations." Metallurgical and Materials Transactions A 36A(5): 1209-1218.
The crystallography and three-dimensional (3-D) morphology of Widmanstätten proeutectoid ferrite precipitates are examined in an Fe-0.12 wt pct C-3.28 wt pct Ni steel isothermally reacted at 650 °C, 600 °C, and 550 °C. This article integrates new orientation mapping (OM) results with the findings of a companion article to this one on the 3-D morphology of proeutectoid ferrite[1] and an earlier transmission electron microscopy (TEM) study which is reanalyzed here in light of the new OM and 3-D results. All of these studies were performed for the same alloy and heat treatments. The 3-D morphologies and distributions of proeutectoid ferrite precipitates are now known to often be quite different from those deduced by conventional two-dimensional (2-D) microscopy techniques. The present crystallographic studies indicate that “primary” ferrite (nucleated directly on prior austenite grain boundaries) forms monolithic single crystals and can be approximated as elongated triangular pyramids. “Secondary” ferrite morphologies can be described as laths and plates branching into the austenite from a thick and/or broad allotriomorphic ferrite base. These secondary Widmanstätten branches are composed of many misoriented crystals with ferrite:ferrite boundaries between them and appear to approach a common orientation as they extend into the austenite grain. Implications of the current findings on existing growth and crystallography models are discussed, and a preliminary hypothesis or mechanism of ferrite formation has been proposed to account for the present observations.
232.
Spanos, G., C.-Y. Hung, et al. (2003). The Morphology, Crystallography, and Formation Mechanism of Grain Boundary Proeutectoid Cementit in High Carbon Steels. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
This paper reviews and brings together in a comprehensive way research by the authors over the last five years which provides new insights into grain boundary proeutectoid cementite formation. In particular, in an Fe-1.3%C-13%Mn alloy, grain boundary cementite "allotriomorphs" do not posess the morphology approximated in the past as double spherical caps or oblate ellipsoids. Instead three dimensional analyses show that this grain boundary cementite exhibits a dendritic morphology. Solid-state dendrites first nucleate at austenite grain edges and/or corners and then during growth spread along austenite grain faces. Reasons why these observations are not made in many previous studies in the literature are discussed. The orientation relationship (OR) between the grain boundary cementite dendrites and at least one of the neighboring austenite grains usually corresponds to one of the previously reported (rational) cementite: austenite ORs, indicating that nucleation occurs so as to minimize the free energy of the cementite critical nucleus. Alternatively, crystallographic analyses show that there is no unique primary dendrite arm growth direction. Implications of these findings on predictive models of microstructual evolution are considered, and a new model for grain boundary proeutectoid cementite formation is proposed.
233.
Spiess, R., L. Peruzzo, et al. (2001). "Development of Garnet Porphyroblasts by Multiple Nucleation, Coalescence and Boundary Misorientation-Driven Rotations." Journal of Metamorphic Geology 19(3): 269-290.
Two types of garnet porphyroblast occur in the Schneeberg Complex of the Italian Alps. Type 1 porphyroblasts form ellipsoidal pods with a centre consisting of unstrained quartz, decussate mica and small garnet grains, and a margin containing large garnet grains. Orientation contrast imaging using the scanning electron microscope shows that the larger marginal garnet grains comprise a number of orientation subdomains. Individual garnet grains without subdomains are small (< 50 µm), faceted and idioblastic, and have simple zoning profiles with Ca-rich cores and Ca-poor rims. Subdomains of larger garnet grains are similar in size to the individual, small garnet grains. Type 2 porphyroblasts comprise only ellipsoidal garnet, with small subdomains in the centre and larger subdomains at the margin. Each subdomain has its own Ca high, Ca dropping towards subdomain boundaries. Garnet grains, with or without subdomains, all have the same Ca-poor composition at rims in contact with other minerals. The compositional zonation patterns are best explained by simultaneous, multiple nucleation, followed by growth and amalgamation of individual garnet grains. The range of individual garnet and garnet subdomain sizes can be explained by a faster growth rate at the porphyroblast margin than in the centre. The difference between Type 1 and Type 2 porphyroblasts is probably related to the growth rate differential across the porphyroblast. Electron backscatter diffraction shows that small, individual garnet grains are randomly oriented. Large marginal garnet grains and subdomain-bearing garnet grains have a strong preferred orientation, clustering around a single garnet orientation. Misorientations across subdomain boundaries are small and misorientation axes are randomly oriented with respect to crystallographic orientations. The only explanation that fits the observational data is that individual garnet grains rotated towards coincident orientations once they came into contact with each other. This process was driven by the reduction of subdomain boundary energy associated with misorientation loss. Rotation of garnet grains was accommodated by diffusion in the subdomain boundary and diffusional creep and rigid body rotation of other minerals (quartz and mica) around the garnet. An analytical model, in which the kinetics of garnet rotation are controlled by the rheology of surrounding quartz, suggests that, at the conditions of metamorphism, the rotation required to give a strong preferred orientation can occur on a similar timescale to that of porphyroblast growth.
234.
Splinter, S. J., N. S. McIntyre, et al. (1993). "An AES and XPS Study of the Initial Oxidation of Polycrystalline Magnesium with Water-Vapor at Room-Temperature." Surface Science 292(1-2): 130-144.
235.
Splinter, S. J., N. S. McIntyre, et al. (1994). "Influence of Ar+ Ion-Bombardment on the Initial Interaction of Water-Vapor with Polycrystalline Magnesium Surfaces." Surface Science 302(1-2): 93-108.
236.
Springer, F. (1998). "Recent developments in automated crystal orientation mapping (ACOM) - quantitative evaluation and graphical representation of individual grain orientation data." Materials Science Forum 273-275: 191-200.
A system is presented which performs fully unattendedly the measurement of the crystal orientations of individual grains using the automated interpretation of Backscatter Kikuchi Patterns (BKP). The features which are necessary to scan a selected area of the specimen surface with a high spatial resolution are described. Several possibilities for a quantitative evaluating of the acquired orientation data and their representation by pseudo-colored maps are shown. A simple estimate of the quality of BKD pattern yields information on the degree of deformation or recrystallization. Methods of quantitative stereological and statistical evaluation of the acquired data are demonstrated. The local texture of small selected areas can be investigated and be described by its statistical functions which are calculated from the achieved orientation data. (Author abstract) [References: 15]
237.
Springer, F. and M. Radomski (1998). "In situ recrystallization of copper studied by individual grain orientation measurement in the SEM." Materials Science Forum: 273-275.
The effect of orientation and misorientation of the individual grains on the recrystallization behavior of deformed copper is investigated. Samples of pure copper which were cold rolled to 95% reduction are annealed in several steps under observation in the SEM. A heating stage has been developed which enables long-term heating experiments in the SEM up to 400 degree C. The samples are annealed step by step. The same area of specimen surface is studied in subsequent stages of recrystallization. Before and after each annealing treatment the crystallographic orientations of the individual grains are measured by interpreting Backscatter Kikuchi Patterns (BKP) using the Automated Crystal lattice Orientation Mapping (ACOM) device. A comparison of the resulting crystal orientation maps yields the changes of structure and local orientation with progress of recrystallization. Recrystallized areas can be distinguished from areas which are not yet recrystallized. It becomes directly visible which grains are growing at the expense of others. (Author abstract) [References: 11]
238.
Springer, F. and N. J. Park (1998). "Inhomogeneous texture distributions imaged by ACOM and X-ray pole figure measurement." Materials Science Forum 273-275: 489-496.
The development of inhomogeneous texture in a deep-drawn aluminum cup and a friction welded aluminum roller has been investigated by ACOM (Automated Crystal Orientation Mapping) and compared with results from x-ray pole figure measurement and ODF analysis with triclinic sample symmetry. After deep drawing the diffracted x-ray intensities are drastically reduced to only about 15% of the initial one, and the spread range of the orientation components are expanded. The sharp cube component of initial texture was retained after deep drawing, but the weak beta fiber has disappeared and some other components are formed. As another example texture changes by frictional bonding, the seam between two parts of a roller has been studied. The rollers were made of Al 6061 and are used in textile industry. The texture was investigated by means of ACOM because the deformed zone during the welding is much narrower. (Author abstract) [References: 8]
239.
Srinivas, M., P. R. Rao, et al. (1989). "On Apparent Pop-in During Ductile Fracture-Toughness Testing Being Related to the Yield-Point Phenomenon in Armco Iron." Scripta Metallurgica 23(9): 1627-1632.
Recently, a method has been devised for measuring boundary orientations using backscattered Kikuchi diffraction (BKD, otherwise known as electron backscattering, (EBS). To illustrate its application, piece of recrystallised 99.0% purity nickel sheet of rectangular cross section and thickness 0.125mm was annealed in vacuum for 1 hour at 1050 degree C so that the resulting grain size was approximately 100 mu m. Geometrical parameters for 47 grain boundaries were measured. The work reported demonstrates that BKD can be efficiently used to measure both the misori
240.
Srivastava, V., J. P. Williams, et al. (2004). "Low stress creep behaviour of 7075 high strength aluminium alloy." Materials Science and Engineering A 382(1-2): 50-56.
Creep behaviour of 7075 aluminium alloy has been investigated in the temperature range 350–410 °C and at applied tensile stresses between 1.8 and 6.3 MPa. The as-received material was thermomechan-ically processed to obtain 48 µm grain size, with grain growth to 78 µm during creep and a thixo-forged sample was also investigated. A transition from a region of low stress exponent (~1) to a higher stress exponent (~5) was observed on increasing the stress above 5 MPa. The measured creep rates at low stresses were normalised for grain growth and found to be within a factor of 2 of the rates expected from the Nabarro–Herring equation. The value of activation energy for creep was found to be close to 147 kJ/mol. The measured rates were found to conform to rates measured at constant strain rates and comparably low stresses for superplastic 7075 aluminium alloy with comparable microstructure.
241.
Stallard, A., D. Shelley, et al. (2005). "The initiation and development of metamorphic foliation in the Otago Schist, Part 2: evidence from quartz grain-shape data." Journal of Metamorphic Geology 23: 443-459.
Shape, size and orientation measurements of quartz grains sampled along two transects that cross zones of increasing metamorphic grade in the Otago Schist, New Zealand, reveal the role of quartz in the progressive development of metamorphic foliation. Sedimentary compaction and diagenesis contributed little to the formation of a shape-preferred orientation (SPO) within the analysed samples. Metamorphic foliation was initiated at sub-greenschist facies conditions as part of a composite S1-bedding structure parallel to the axial planes of tight to isoclinal F1 folds. An important component of this foliation is a pronounced quartz SPO that formed dominantly by the effect of dissolution–precipitation creep on detrital grains in association with F1 strain. With increasing grade, the following trends are evident from the SPO data: (i) a progressive increase in the aspect ratio of grains in sections parallel to lineation, and the development of blade-shaped grains; (ii) the early development of a strong shape preferred orientation so that blade lengths define the linear aspect of the foliation (lineation) and the intermediate axes of the blades define a partial girdle about the lineation; (iii) a slight thinning and reduction in volume of grains in the one transect; and (iv) an actual increase in thickness and volume in the survivor grains of the second transect. The highest-grade samples, within the chlorite zone of the greenschist facies, record segregation into quartz- and mica-rich layers. This segregation resulted largely from F2 crenulation and marks a key change in the distribution, deformation and SPO of the quartz grains. The contribution of quartz SPO to defining the foliation lessens as the previously discrete and aligned detrital quartz grains are replaced by aggregates and layers of dynamically recrystallized quartz grains of reduced aspect ratio and reduced alignment. Pressure solution now affects the margins of quartz-rich layers rather than individual grains. In higher-grade samples, therefore, the rock structure is characterized increasingly by segregation layering parallel to a foliation defined predominantly by mica SPO.
242.
Stallybrass, C. and G. Sauthoff (2004). "Ferritic Fe–Al–Ni–Cr alloys with coherent precipitates for high-temperature applications." Materials Science and Engineering A 387-389: 985-990.
Strengthening by a homogeneous distribution of a second phase is a concept that is widely employed in high-temperature materials. It is shown that suitable microstructures can be obtained in the Fe–Al–Ni–Cr system with ordered (Ni, Fe)Al precipitates in a ferritic matrix. These precipitates lead to higher levels of yield strength at elevated temperatures than conventional iron-base high-temperature alloys. The results show that the investigated materials exhibit the highest yield strength after solution heat treatment and lower values after aging, indicating precipitation of fine particles during air cooling. The decrease of yield strength in the latter case was more pronounced for alloys with a high precipitate content than for leaner alloys.
243.
Stanford, N. and P. S. Bate (2004). "Crystallographic variant selection in Ti-6Al-4V." Acta Materialia 52(17): 5215-5224.
Transformation textures in the two-phase alloy Ti-6Al-4V have been studied. Samples were heated into the fully β phase condition and then slow cooled to allow diffusional transformation to α. This produced a microstructure of grain boundary α encircling colonies of Widmanstaetten α. Electron backscattered diffraction (EBSD) texture measurements showed that the α texture was markedly sharper than that calculated on a basis of equal variant probability, indicating that significant variant selection was occurring during diffusional transformation. Investigation of the αvariants produced across prior β grain boundaries has shown that the selection of variants during transformation is highly dependant on the crystallography of those boundaries. The effect of this crystallographic variant selection on the transformation texture has been modelled.
244.
Stanford, N. and P. S. Bate (2005). "Crystallographic variant selection in α–ß brass." Acta Materialia 53(3): 859-867.
The transformation texture of alpha / beta brass with a diffusional Widmanstatten alpha growth morphology has been investigated. Electron micrographs and electron backscattered diffraction was used to determine that the orientation relationship between the beta phase and the alpha associated with nucleation at beta grain boundaries was 44.3 degrees <116>. Crystallographic variant selection was observed across those prior beta / beta grain boundaries, but this has little effect on the transformation texture due to the crystal symmetry. The effect of the crystallographic variant selection on texture is further weakened by nucleation of diffusional transformed alpha in the grain interior.
245.
Stanford, N. and P. S. Bate (2005). The Martensitic Transformation Texture in Ti-6Al-4V. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The transformation texture associated with martensite formation in the titanium alloy Ti-6Al-4V has been investigated. Samples were heated into the fully β phase and quenched to form a microstructure of very fine α' martensite with no evidence of diffusional transformation at the prior β grain boundaries. EBSD texture measurements on the martensite showed that within each prior β grain, although typically all 12 variants of α’ were formed, the fractions of variants was far from uniform. The α’ texture was markedly different from values calculated using equal variant probability, also indicating that significant variant selection was occurring during martensitic transformation. This effect was modelled on the basis of elastic interaction between martensite events.
246.
Stanford, N., A. Djakovic, et al. (2004). "Seeding of single crystal superalloys––role of seed melt-back on casting defects." Scripta Materialia 50: 159-163.
Single crystal seeds of the nickel-base superalloy CMSX-4 have been partially melted in a temperature gradient and then quenched. Small islands of random orientation are observed throughout the melted-back semi-solid. These random orientations appear to be pinched-off secondary dendrite arms, but there is no evidence that they are transported ahead of the dendrite tips to nucleate stray grains during directional solidification.
247.
Stanford, N., D. Dunne, et al. (2003). "Deformation and annealing of (011)[011] oriented Al single crystals." Acta Materialia 51(3): 665-676.
High purity Al single crystals of the (011)[011] orientation have been deformed in plane strain compression in a channel die. Deformation was carried out at a strain rate of 0.01 s-1 to true strains of 0.5 and 1.0 and at temperatures of 25, 200 and 300°C. The as-deformed microstructure has been characterized using electron backscattered diffraction (EBSD) and X-ray diffraction (XRD). No recrystallization was detected after deformation, and the deformation texture analysis showed that the stability of the orientation decreased with increasing temperature, contrary to reports for other orientations. Annealing was carried out for various times at 300°C. Nucleation of recrystallization exhibited periodicity, with distinct bands of recrystallized grains forming parallel to the transverse direction. This recrystallized microstructure has been examined using EBSD. A model is proposed to account for the origin of the periodicity of the nucleation and the retention of rods or cylinders of unrecrystallized material after significant annealing times.
248.
Stanford, N., D. Dunne, et al. (2003). "Effect of orientation stability on recrystallization textures of deformed aluminium single crystals." Materials Science and Engineering A 348(1-2): 154-162.
High purity Al single crystals of the Cube (001) 100 and rotated Cube (011) 011 orientations have been deformed in plane strain compression in a channel die. Deformation was carried out at temperatures between 25 and 600 deg C up to strains of 1.2. The as-deformed microstructure has been characterized using electron microscopy and electron backscattered diffraction (EBSD). Annealing was carried out for various times and temperatures. The recrystallized microstructure has been studied using electron microscopy, and the orientation of recrystallized grains determined using EBSD After cold deformation and annealing both orientations exhibited a random recrystallization texture component. After hot deformation both orientations retained a similar annealing texture to their starting deformation texture. The annealing texture of deformed single crystals was found to be more sensitive to the temperature of deformation than the stability of the orientation.
249.
Starink, M. J. and S. C. Wang (2003). "A model for the yield strength of overaged Al-Zn-Mg-Cu alloys." Acta Materialia 51(17): 5131-5150.
A model for the yield strength of multi-component alloys is presented and applied to overaged Al-Zn-Mg-Cu alloys (7xxx series). The model is based on an approximation of the strengthening due to precipitate bypassing during precipitate coarsening and takes account of ternary and higher order systems. It takes account of the influence of supersaturation on precipitation rates and of volume fraction on coarsening rates, as well crystallographic texture and recrystallisation. The model has been successfully used to fit and predict the yield strength data of 21 Al-Zn-Mg-Cu alloys, with compositions spread over the whole range of commercial alloying compositions, and which were aged for a range of times and temperatures to produce yield strengths ranging from 400 to 600 MPa. All but one of the microstructural and reaction rate parameters in the model are determined on the basis of microstructural data, with one parameter fitted to yield strength data. The resulting accuracy in predicting unseen proof strength data is 14 MPa. In support of the model, microstructures and phase transformations of 7xxx alloys were studied by a range of techniques, including differential scanning calorimetry (DSC), electron backscatter diffraction (EBSD) in an SEM with a field emission gun (FEG-SEM). Copyright 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
250.
Starink, M. J. and X. M. Li (2003). "A Model for the Electrical Conductivity of a Peak-Aged and Overaged Al-Zn-Mg-Cu Alloys." Metallurgical and Materials Transactions A 34A(4): 899-911.
A physically based model for the electrical conductivity of peak-aged and overaged Al-Zn-Mg-Cu (7xxx series) alloys is presented. The model includes calculations of the n- and the S-phase solvus (using a regular-solution model). taking account of the capillary effect and n coarsening. It takes account of the conductivity of grains (incorporating dissolved alloying elements, undissolved particles and precipitates) and solute-depleted areas at the grain boundaries. Data from optical microscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM) are consistent with the model and its predictions. The model has been successfully used to fit and predict the conductivity data of a set of 7xxx alloys including both Zr-containing alloys and Cr-containing alloys under various aging conditions, achieving an accuracy of about 1 pct. in predicting unseen conductivity data from this set of alloys.
251.
Steeds, J. W. and J. P. Morniroli (1992). "Selected Area Electron-Diffraction (Saed) and Convergent Beam Electron-Diffraction (Cbed)." Reviews in Mineralogy 27: 37-84.
252.
Stobbs, W. M. (1984). "Problem Oriented Transmission Electron-Microscopy." Journal of Microscopy - Oxford 136(NOV): 137-151.
253.
Stockemer, J. and P. Vanden Brande (2003). "Crystallization of a Cold-Rolled Low-Carbon Steel by Cold-Plasma-Discarge Rapid Annealing." Metallurgical and Materials Transactions A 34A(No. 6): 1341-1348.
A new annealing technology has been developed by the authors in order to conduct fast steel annealing. This process consists of steel heating by cold- plasma discharge. It allows the opportunity for new annealing cycles with higher heating rates (up to 300 K/s), shorter soaking times, and controlled cooling rates, so that well crystallized samples have been achieved in less than several seconds of process time. This article reports the influence of various parameters of the annealing cycle (heating rate, maximum annealing temperature, and cooling rate on the recrystallization and properties of a cold-rolled low-carbon steel. This study shows that the annealing time can be significantly reduced using this new technology, compared to the industrial continuous annealing technology used today, to obtain equivalent metallurgical properties.
254.
Storey, C. D. and D. Prior (2005). "Plastic Deformation and Recrystallization of Garnet: A Mechanism to Facilitate Diffusion Creep." Journal of Petrology 46(12): 2593-2613.
Elongate and deformed garnets from Glenelg, NW Scotland, occur within a thin shear zone transecting an eclogite body that has undergone partial retrogression to amphibolite facies at circa 700°C. Optical microscopy, back-scattered electron imaging, electron probe microanalysis and electron back-scatter diffraction reveal garnet substructures that are developed as a function of strain. Subgrains with low-angle misorientation boundaries occur at low strain and garnet orientations are dispersed, around rational crystallographic axes, across these boundaries. Towards high-strain areas, boundary misorientations increase and there is a loss of crystallographic control on misorientations, which tend towards random. In high-strain areas, a polygonal garnet microstructure is developed. The garnet orientations are randomly dispersed around the original single-crystal orientation. Some garnet grains are elongate and Ca-rich garnet occurs on the faces of elongate grains oriented normal to the foliation. Commonly, the garnet grains are admixed with matrix minerals, and, where in contact with other phases, garnet is well faceted. We suggest that individual garnet porphyroclasts record an evolution from low-strain conditions, where dislocation creep and recovery accommodated deformation, through increasing strain, where dynamic recrystallization occurred by subgrain rotation, to highest strains, where recrystallized grains were able to deform by diffusion creep assisted grain boundary sliding with associated rotations.
255.
Storjohann, D., O. M. Barabash, et al. (2005). "Fusion and Friction Stir Welding of Aluminum-Metal-Matrix Composites." Metallurgical and Materials Transactions A 36A(11): 3237-3247.
Microstructure evolutions and degredations of aluminum-metal-matrix composites during fusion welding were studied and compared with thermodynamic calculations. In fusion welds of Al2O3-reinforced composites, the decomposition of Al2O3 was observed. In fusion welds of SiC whisker-reinforced composites, the decomposition of SiC to Al4C3 + Si by reaction with molten aluminum occurred. These phenomena led to unacceptable fusion welds in aluminum-metal-matrix composites. Successful welds were produced in the same composites by friction stir welding (FSW). Significant reorientation of SiC whiskers close to the boundary of the dynamically recrystallized and thermomechanically affected zone (TMAZ) was observed. The small hardening in the dynamically recrystallized region was attributed to the presence of dislocation tangles in between SiC whiskers.
256.
Storojeva, L., D. Ponge, et al. (2004). "Development of microstructure and texture of medium carbon steel during heavy warm deformation." Acta Materialia 52(8): 2209-2220.
The microstructure and texture development of a medium-carbon steel (0.36% C) during heavy warm deformation (HWD) was studied using scanning electron microscopy and electron back scattering diffraction. The spheroidization of pearlite is accelerated due to the HWD, which leads to the formation of completely spheroidized cementite already after the deformation and coiling at 873 K (600 degrees C). The homogeneity of the cementite distribution depends on the cooling rate and the coiling temperature. The cooling rate of about 10 K/s (ferrite-pearlite prior to HWD) and deformation/coiling at 943-973 K (670-700 degrees C) lead to a homogeneous cementite distribution with a cementite particle size of less than 1 µm. The ferrite softening can be attributed to continuous recrystallization. Even up to fairly high deformation/coiling temperatures of 983 K (710 degrees C) the texture consists of typical deformation components. During the continuous recrystallization the amount of high angle grain boundaries can increase up to 70% with a ferrite grain size of 1-3 µm. An increase of the cooling rate up to 20 K/s (ferrite-pearlite-bainite prior to HWD) deteriorates the homogeneity of the cementite distribution and the softening of ferrite in the final microstructure.
257.
Storojeva, L., R. Kaspar, et al. (2003). Ferritic-Pearlitic Steel with Deformation Induced Spheroidized Cementite. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
The study of medium-carbon steel (0.35% C) with a deformation induced globular cementite produced by a heavy warm deformation (HWD) was carried out as a potential substitution of a conventional quenching and tempering (QT) or soft annealing (SA). Specimens for all three treatments were re-heated into the austenite range and hot deformed at the same temperature and at the same strain to get an optimum conditioning of the initial austenite structure. The HWD sample were cooled with cooling rates ~ 7 - 8 K/s and heavily deformed (ε~0.6) at the temperatures below the g-a transformation (600 - 710° C), with a subsequent simulated coiling at the deformation temperatures. The QT samples were tempered at temperatures 600 - 670° C. The SA samples were annealed at 710° C for 16 h. The HWD allows to accelerate essentially the spheroidization of lamellar pearlite. The subsequent soaking at the suitable coiling temperature leads to a rather homogeneous distribution of a fine dispersed cementite in a recrystallized fine grain ferritic microstructure. As a result, the mechanical properties of the HWD samples proved to be well comparable to those after QT.
258.
Stout, J. J. and M. A. Crimp (1992). "Abnormal Grain-Growth in Textured Feal Intermetallics." Materials Science and Engineering A 152(1-2): 35-340.
259.
Stout, M. G., S. R. Chen, et al. (1998). Mechanisms responsible for texture development in a 5182 aluminum alloy deformed at elevated temperature. 1998 Minerals, Metals and Materials Society (TMS) fall meeting, Rosemont, Illinois, USA.
The textures that develop in a 5182 aluminum alloy as a result of monotonic high-temperature compression have been investigated. The authors found that the deformation texture was a function of temperature. For compressive deformation at 300 C and below the material formed the classic (101) deformation texture, while the material develops a texture that is a combination of the classical uniaxial compression deformation texture, (101), and static recrystallization texture, (001), as a result of the deformation alone when the deformation temperature was at and above 400 C. The investigation has focused on determining the mechanism responsible for the development of this unusual progression of deformation textures. In addition the authors have performed orientation imaging microscopy (OIM) to identify the shapes of grains with particular orientations and grain-to-grain orientation relationships. The conclusions are summarized as follows: The texture development is not a result of static processes, i.e. static recrystallization at the various hold times altered neither the textures nor the constitutive behavior. Simulation using a crystal plasticity model indicates that the combination of a cube component prevalent in the original texture, slip activity on 011 planes, and increased rate sensitivity leads to a combined (001) and (101) texture. Finally, the microscopic OIM results are consistent with these observations.
260.
Straumal, B. B., S. A. Polyakov, et al. (2005). "Faceting of S3 and S9 grain boundaries in Cu–Bi alloys." Acta Materialia 53(2): 247-254.
The faceting of S3 and S9 tilt grain boundaries (GBs) has been studied in bicrystals of pure Cu and Cu–Bi alloys containing 2.5 × 10-3, 10 × 10-3 and 16 × 10-3 at.% Bi. The S3(1 0 0), S9(1 0 0), S9(-1 1 0), and S9(-1 2 0) facets and non-CSL S3 82° 9R facet were observed, where S is the inverse density of coincidence sites. The ratio between GB energy, sGB, and surface energy, ssur, was measured by atomic force microscopy using the GB thermal-groove method. The GB energy and thermal-groove deepening rate increased slightly between 0 and 10 × 10-3 at.% Bi for all facets studied. However, between 10 × 10-3 and 16 × 10-3 at.% Bi the GB energy increased dramatically [from a factor 2 for the S9(1 1 0) facet to 15 times larger for the S3(1 0 0) facet]. The thermal-groove deepening rate also increased by a factor of 10 in this concentration range. This change corresponds well with the GB solidus line (i.e., the formation of a stable layer of a liquid-like GB phase called GB prewetting) observed previously. Wulff diagrams were constructed using measured sGB/ssur values.
261.
Strom, E. and J. Zhang (2005). "Mechanical anisotropy and segregation in Mo5Si3 studied by EBS." Intermetallics 13(3-4): 367-372.
The cracking behaviour of indented areas in monolithic Mo5Si3 and segregation in Cr-alloyed Mo5Si3 have been studied by electron back-scattering diffraction (EBSD) in a scanning electron microscope (SEM). Vickers indentation of Mo5Si3 indicates preferred cleavage across the 001 direction, resulting in chipping if the indent is normal to the (001) plane. The other two alloyed Mo5Si3-based compounds studied in this work, i.e. Mo3CrzSi3 and Mo3TizSi3, behave differently during heat treatment. Mo3CrzSi3, on the one hand, shows unexpected additional X-ray reflections together with broadening of reflections after annealing, when compared to its as-cast condition. Observations of increased segregation upon annealing are made, presumably by a separation into Cr-lean and Cr-enriched (Mo,Cr)5Si3, especially in the <100> directions according to EBSD Segregation of Cr is linked to additional reflections in X-ray diffraction (XRD). Mo3TizSi3, on the other, seems to be in chemical equilibrium in the as-cast state according to energy dispersive spectrometry (EDS) measurements, and there is little difference in XRD between as-cast and heat treated alloys.
262.
Su, P., M. Ding, et al. (2005). Effects of reflow on the microstructure and whisker growth propensity of Sn finish. 2005 Proceedings. 55th Electronic Components and Technology Conference, Lake Buena Vista, Florida, USA, IEE.
The initiative of removing Pb from materials sets within the microelectronics industry has created many challenges for research and development. One of the issues is to replace the Pb-containing finish with a Pb-free finish for leaded packages. Pure Sn and alloys with high Sn content have been the leading choices for many manufacturers. These finishes, however, have the tendency to spontaneously grow whiskers on the surface, which is considered by some to be a potential reliability concern as the whiskers can continuously grow and may cause shorting between leads. In this study, leaded components with as-plated Sn finish and reflowed Sn finish are subjected to several Sn whisker acceleration tests including air-to-air thermal cycling and temperature/humidity storage. The results indicate that the whisker growth propensity on the two different finishes is rather different. Microstructure analysis of the Sn finish is also performed with scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). Significant microstructure differences are observed between the as-plated and the reflowed Sn finish including grain size, grain orientation, and intermetallic compound (IMC) thickness. As Sn whisker growth is mostly a stress related phenomenon, these findings of microstructure change are used to interpret the process of stress buildup and relief in both as-plated and reflowed Sn. Additionally, at room temperature Sn has a very anisotropic lattice (body centered tetragonal) and this property contributes greatly to the stress concentration in the Sn finish. The implication of this property on Sn whisker growth is also discussed.
263.
Su, S. F., J. C. Huang, et al. (2002). "Electron-Beam Welding Behavior in Mg-Al-Based Alloys." Metallurgical and Materials Transactions A 33A(5): 1461-1473.
The electron-beam-welding (EBW) behaviors of pure Mg and the AZ31, AZ61 and AZ91 Mg alloys are examined in this study, in terms of fusion-zone characteristics, grain structures, texture evolution, and joint efficiency. With increasing Al content, the Mg-based materials were found to be more easily fusion welded. The AZ91 alloy could be welded using a beam power of 2200 W and a weld speed of 16 mm/s, resulting in a weld depth of 29 mm with a fusion-zone aspect ratio of 8.2. The grains inside the fusion zone were nearly equiaxed in shape and ~10 µm in size, due to the rapid cooling rate. Extended partial melting zones were observed in alloys with high solute contents, such as AZ61 and AZ91. The postweld tensile strength of the Mg alloys could recover back to ~80 - 100 percent of the original strength. The texture in the fusion zone was traced by x-ray diffraction (XRD) and electron backscattered diffraction (EBSD). The grain orientations inside the rapidly solidified electron-beam-welded fusion zones are still rather diversely distributed. The a1-, a2-, and a3- axes of some grains tend to align at 30 or 90 deg with respect to welding direction, and the c-axis tends to align along the plate normal direction. The influence of surface tension on the weld top-surface appearance and weld depth was not pronounced for the current four Mg materials. Instead, differences in the solidus temperatures and thermal conductivity should be the primary factors.
264.
Su, Y.-H., L. Chang, et al. (2005). "The orientation effect of silicon grains on diamond deposition." Diamond and Related Materials 14(11-12): 1753-1756.
Diamond deposition on mirror-polished polycrystalline silicon substrates which have grains in various orientations has been investigated using electron backscatter diffraction (EBSD) method with scanning electron microscopy (SEM). Diamond was deposited by microwave plasma chemical vapor deposition with application of a negative bias voltage on the substrate. The evidence from systematic SEM observations shows that silicon orientation determined by EBSD has a strong effect on diamond nucleation. In general, the diamond nucleation density on Si grains oriented close to <100> is the highest, while it is the lowest for those grains close to <111>, under the same experimental conditions for deposition. The same phenomena have been observed in the range of methane concentration from 2% to 4% in hydrogen.
265.
Suery, M. and B. Baudelet (1980). "Hydrodynamical Behavior of a 2-Phase Superplastic Alloy - Alpha-Beta-Brass." Philosophical Magazine A 41(1): 41-64.
266.
Sugimoto, K., A. Hayakawa, et al. (2003). Development of High Strength Low Alloy TRIP-Aided Steels with Ultra Fine Grain. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
The effects of thermomechanical processing and prior structure on microstructure and retained austenite characteristics of high-strength low alloy 0.20C-1.5Si-1.5Mn TRIP-aided steels were investigated to enhance the workability limit. Ultra fine polygonal ferrite grain of 1 to 2 µm in diameter were completed inside prior martensite lath structure ajacent to interlath retained austenites in the steels with the prior structure of martensite single phase which were subjected to 30-50% reduction it interciritical annealing temperatures between 760 and 820° C, followed by austempering at 375 to 450° C for 100 seconds. Under the same processing conditions, volume fraction of retained austenite was significantly increased with a small decrease in its carbon concentration. It was found in the steels that relatively thick austenite plates recrystallized during intercritical annealing suppressed the migration of prior martensite lath boundary and the resultant grain growth of recrystallized polygonal ferrite. Also, it was confirmed by EBSP analysis that a difference in orientation between the ultrafine polygonal ferrite grains was relatively large.
267.
Sugiyama, M. (2001). "Development of Microstructure Control Materials with Progress of Cyrstallographic Orientation Analysis." Materia Japan 40(7): 611.
268.
Suh, D.-W., C.-S. Oh, et al. (2005). "Limit of Ferrite Grain Refinement by Severe Plastic Deformation of Austenite." Metallurgical and Materials Transactions A 36A(4): 1057.
High-angle grain-boundary spacing in deformed austenite is analyzed using Ni-30Fe alloy to explain the change of ferrite grain size by severe plastic deformation (SPD) of austenite in low carbon steel. It is suggested that constant high-angle grain-boundary spacing in deformed austenite resulting from dynamic recrystallization (DRX) or geometric DRX is responsible for the limit of ferrite grain refinement over a certain level of plastic deformation of austenite.
269.
Suh, D.-W., J.-H. Kang, et al. (2002). "Evaluation of the deviation angle of ferrite from the Kudjumov–Sachs relationship in a low carbon steel by EBSD." Scripta Materialia 46: 375-378.
A method to evaluate the orientational relationships between ferrite and the mother austenite grain is proposed. The deviation angles from the Kudjumov–Sachs relationships were evaluated based on the orientation of the austenite grains, which is indirectly determined from the orientations of martensite packets formed within the austenite grains.
270.
Suh, D.-W., J.-Y. Cho, et al. (2000). Effects of Uniaxial Stress on the Nucleation Behavior of Ferrite from Deformed Austenite. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
The effects of external stress on the nucleation behaviors of low carbon steel were studied. The nucleation rate of ferrite under stressed condition is more than doubled when compared with stress free condition, however, little effects of external stress on the growth rate of ferrite were observed. The increase of nucleation rate in stressed condition is observed at austenite/ferrite boundaries as well as austenite grain boundaries. The weakening of orientation relationship due to the interaction between volume expansion accompanying ferrite transformation and external stress are thought to be responsible for the accelerated nucleation rate of ferrite.
271.
Suh, D.-W., J.-Y. Cho, et al. (2004). "Effect of Initial Grain Size of Austenite on Hot-Deformed Structure of Ni-30Fe Alloy." Metallurgical and Materials Transactions A 35A(11): 3399-3408.
The microstructural evolutions of Ni-30Fe alloys during hot deformation are investigated. Hot-deformed structures of Ni-30Fe alloys with initial austenite grain sizes of 20 and 140 µm are examined under various compressive strains and deformation temperatures. As the initial austenite grain size decreases, dynamic recrystallization (DRX) occurs at lower compressive strain and lower deformation temperature. At deformation temperatures where dynamic recovery occurs instead of the DRX, hot-deformed structures consist of recovered elongated grains until fine-equiaxed grains are evolved by geometric DRX. Critical compressive strain for the geometric DRX decreases with the decrease of initial austenite grain size. Geometric DRX is evolved by the impingement of serrated grain boundaries. The decrease of initial grain size is considered to reduce the critical compressive strain needed for the impingement of serrated grain boundaries. The changes in the effective thickness of austenite grain according to the compressive deformation are examined, and the effects of the restoration process on the effective thickness of austenite grain are discussed.
272.
Suh, D.-W., S.-Y. Lee, et al. (2003). Rapid grain growth of hot extruded Al-Zn-Mg-Cu-(Sc) alloy during heat treatment. 3rd International Symposium on Designing, Processing and Properties of Advanced Engineering Materials: ISAEM-2003, Jeju, South Korea, Trans Tech Publications.
Rapid grain growth and artificial aging characteristics during heat treatment is investigated for hot extruded Al-Zn-Mg-Cu-(Sc) alloys. Two Al-0.1 wt%Sc alloys with different alloying element content are hot extruded to make T-shape bars at 380 degrees C, and then the bars are solution treated for 2 hours at 480 degrees C followed by artificial aging for 24 hours at 120 degrees C. Microstructural evolution of the hot extruded bar is analyzed with optical microscope and electron back scattered diffraction (EBSD) mapping. Two kind of extruded bar shows different grain growth behavior at surface region and different artificial aging characteristics. The interaction between the precipitates and the grain growth during the heat treatment is thought to be responsible for the different grain growth behavior.
273.
Suh, D.-W., S.-Y. Lee, et al. (2004). "Microstructural evolution of Al–Zn–Mg–Cu–(Sc) alloy during hot extrusion and heat treatments." Journal of Materials Processing Technology 155-156: 1330-1336.
The microstructural evolution during hot extrusion and post heat treatment was investigated for two kind of Al–Zn–Mg–Cu–(Sc) alloy and AA7075. The microstructure of as-extruded bar is mainly comprised of recovered structure for all alloys, however, different restoration processes are observed during post heat treatment. For AA7075 and S1, which contains 0.1% Sc with relatively higher Zn and Cu content than S2, recovery still proceeds during the heat treatment, while the recrystallization becomes main restoration process during the heat treatment for S2. The differences in abnormal grain growth and hardening behavior between S1, AA7075 and S2 during the heat treatment are discussed in connection with the restoration processes and resultant microstructures.
274.
Suikkanen, P. P., J. I. Komi, et al. (2005). "Processing low and ultra-low carbon bainitic steels with excellent property combinations." Materials Science Forum 500-501: 535-542.
Six experimental low and ultra-low carbon C-Mn-Mo-Nb-B and one conventional TMCP steel heats have been prepared to study the effects of chemical composition and hot deformation on the microstructure and the strength-toughness properties. In physical simulation tests, it was found that the deformation of austenite below the non-recrystallization temperature enhances the formation of higher-temperature bainitic morphologies and polygonal ferrite. On the other hand, hardness exhibits relatively low sensitivity to the degree of deformation below Tnr, whereas the deformation results in a distinct refinement in the microstructures, as determined by SEM-EBSD measurements, suggesting an improvement in the impact toughness. Simultaneous alloying with Mo-Nb-B seemed to be most efficient to provide high hardness and strength. Hot rolling trials indicated that the yield strength in the range 500-700 MPa with the excellent toughness down to -80°C can be achieved in low carbon (approximately = 0.03%) bainitic grades.
275.
Sumigawa, T., T. Kitamura, et al. (2004). "Slip behaviour near a grain boundary in high-cycle fatigue of poly-crystal copper." Fatigue & Fracture of Engineering Materials & Structures 27: 495-503.
276.
Sun, C. C. and N. Ryum (1992). "Crystallographic Aspect of Cellular Solidification." Materials Characterization 29(4): 381-386.
277.
Sun, J., Y. Liu, et al. (2005). "Texture evolution of deep-drawing sheet St15 during recrystallizaiton annealing." Beijing Keji Daxue Xuebao (Journal of University of Science and Technology Beijing) 27(1): 61-64.
Electrical back scatter pattern (EBSP) was used to investigate the texture evolution rule of deepdrawing sheet St15 during recrystallization annealing. When the heating rate is 30 deg C/h, the recrystallization temperature of deep-drawing sheet St15 is about 560 deg C, the recrystallization finishing time is nearly 2h, and the strongest component of the recrystallization texture is {100} < 110 >. gamma fibre texture in St15, especially {111} < 112 >, strengthens with incresing the annealing temperature. When the holding temperature is 700 deg C, {111} < l10 > texture in St15 strengthens with increasing the annealing time, and after holding for 4 h {111} < 112 > texture gradually. When the holding time reaches 13 h, a satisfied annealing texture is achieved.
278.
Sun, L., A. Liu, et al. (2005). "An electron back-scattering diffraction system and its data processing software." Chinese Journal of Stereology and Image Analysis 10(4): 253-256.
This paper describes an electron backscattering diffraction system, which has been successfully developed for a JSM-840 SEM at GRINM. The design of the system is reasonable, and the construction is compact. The CCD sensitivity of the system is 5 µlux at live video rate, and 10 µlux for the normal integration mode, with a CCD resolution of 512dpi. The highest resolution of the scanning card is 4096 x 4096. The system is easy to operate, safe and reliable. The diffraction pattern bands can be automatically identified and displayed indexed by using appropriate software. EBSD data for crystal orientation analyses can be shown as pole figures, inverse pole figures (sample normal and transverse directions), crystal orientation maps and orientation distribution functions, together with an electron micrograph of the area from which the orientation data are collected.
279.
Sun, P. L., P. W. Kao, et al. (2000). Effect of Channel Angle on the Microstructural Evolution in Aluminum Processed by Equal Channel Angular Extrusion. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
Commercially pure 1050 Al was subjected to equal channel angular extrusion (ECAE) by route C with the channel intersection angles of 90° and 120°. Specimens with one and two pressing passes, and with a same strain level were used to compare the difference of microstructures produced by the two dies. TEM and EBSD (electron back scattered diffraction) were used to observe the evolution of these structures. It is found the effect of channel angle on the misorientation distribution of the generated boundaries is mainly on the low angle range.
280.
Sun, S., B. L. Adams, et al. (2000). "Observations of lattice curvature near the interface of a deformed aluminum bicrystal." Philosophical Magazine A 80(1): 9-25.
Reported here is a study of the pattern of lattice curvature near the interface of deformed high-purity aluminium (99.9999%) bicrystals of specified crystallographic character (large-angle random). Curvature data are obtained from electron baskscattering diffraction pattern observations using orientation imaging microscopy. The concept of geometrically necessary dislocations (GNDs) is used as the central tool in the description of the observations. The samples studied were channel-die compressed perpendicular to the interface to plastic strain levels of 0.1 and 0.3. At a strain level of 0.1 the primary observation is the development of a pile-up of GNDs (i.e. lattice curvature) near the interface. At the higher strain level of 0.3, however, a dramatic change in the distribution is observed. The nature of this change suggests that the interface has absorbed (or emitted) some components of the nearby GND field, with an accompanying change in the local character of the interface towards a broader dispersion of misorientation character.
281.
Suo, H., J.-Y. Genoud, et al. (2002). "Mechanically reinforced {1 1 0}<110> textured Ag/Ni-alloys composite substrates for low-cost coated conductors." Physica C 372-376: 835-838.
New, reinforced {1 1 0}<110> textured Ag/Ni-alloys composite ribbons were developed as possible substrates for coated conductors without any buffer layer. The texture quality and tensile strength were investigated. A new technique to bond the Ag and Ni or alloy layers through a Cu foil was presented. The Ag/Ni-alloys composite ribbons were fabricated by choosing proper sintering processing to bond the different layers followed by cold rolling and recrystallization. A thin Cu foil was intercalated between the initial Ag and Ni or alloy pieces to get a tough bond. A unique and stable {1 1 0}<110> annealing texture was obtained in 300 µm thick Ag/Ni composite ribbon after annealing. X-ray ODF analysis and EBSD measurements in the top Ag layer showed distribution of misorientation angles around 10 – 15°. A {1 1 0}<110> texture was also found in ribbons as thin as 50 µm, which cannot be obtained with pure Ag ribbons. A pronounced reduction of Ag amount was obtained in 60 µm thick Ag/NiCrV ribbons, with a textured Ag top layer being as thin as 7 µm. The amount of Ag was decreased by 75% compared to pure Ag ribbons of the same thickness. A strong enhancement of the mechanical properties was observed. The yield strength s0.2 at 77 K was 220 MPa for Ag/NiCrV ribbons, i.e. considerably higher than the 30 MPa for pure Ag ribbons.
282.
Sutliff, J. A. (1993). Facet crystallography by electron diffraction in the SEM. Annual Meeting, Microscopy Society of America., Cincinnati, Ohio, Publ by San Francisco Press Inc, San Francisco, CA, USA.
To determine the crystallographic plane of a surface facet, it is necessary to determine the orientation of the grain and the orientation of the facet plane relative to the grain. A rapidly growing technique which can be applied to the problem of facet crystallography in small grain size material is the electron back-scattering pattern (EBSP) technique in the SEM. This technique can be applied in a Laue-like fashion, with the added SEM benefits of high resolution imaging and beam positioning. Discussed in the paper is the application of the EBSP technique to facet analysis. [References: 2]
283.
Sutliff, J. A. (1994). Diffraction in the SEM: A significant role in materials research. Annual Meeting, Microscopy Society of America.
The use of electron diffraction in the scanning electron microscopy (SEM), particularly by the Electron Back-Scattering Pattern (EBSP) technique, has matured sufficiently to command a significant role in the materials research laboratory. The unique combination of high spatial resolution of the analyses, modest restrictions on sample size and preparation, quantitative nature of the experiment results, ease of experiment, and high sample throughput have produced a new demand for SEM diffraction facility. The current developments of the SEM diffraction systems are presented in the paper. [References: 6]
284.
Sutliff, J. A. and B. P. Bewlay (1996). Orientation imaging of a Nb-Ti-Si directionally solidified in-situ composite. Microscopy And Microanalysis 1996. G. W. Bailey, J. M. Corbett, R. V. W. Dimlich, J. R. Michael and N. J. Zaluzec. San Francisco, San Francisco Press, Inc.: 350-351.
In this paper we report on the microstructural characterization of a directionally solidified (DS)Nb-Ti-Si alloy. The solidified ingot had a nominal composition of Nb-33 at%Ti- 16 at% Si and was grown using the Czochralski technique with growth rate of 5 mm/min. The as-solidified ingot was approximately 50 mm long with a 10 mm diameter. The microstructure was examined using backscatter electron imaging and the microtexture of each of the phases was determined using the Electron BackScattering Pattern (EBSP) technique for electron diffraction in the scanning electron microscope. The details of the experiments are similar to those we have reported previously. Automated EBSP scans were acquired in order to map the local texture (microtexture) over most of a transverse cross-section through the ingot.
285.
Sutliff, J. A., B. P. Bewlay, et al. (1994). Facet crystallography of fractured V(2.7 wt% Si) solid solution. Fifty-Second Annual Meeting Microscopy Society of America/Twenty-Ninth Annual Meeting Microbeam Analysis Society, New Orleans, LA, San Fancisco Press, Inc.
Results on the fracture surface fractography and fracture facet crystallography of an arc-melted V(2.7 wt% Si) solid solution alloy fractured in bending is presented. [References: 4]
286.
Sutou, Y., T. Omori, et al. (2002). "Enhancement of Superelasticity in Cu-Al-Mn-Ni Shape-Memory Alloys by Texture Control." Metallurgical and Materials Transactions A 33A(No. 9): 2817-2824.
A significant improvement in the degree of superelasticity in Cu-Al-Mn ductile polycrystalline alloys has been achieved through the addition of Ni and the control of the recrystallization texture by thermomechanical processing, which contain the annealing in the fcc(a) + bcc(ß) two-phase region, followed by heavy cold reductions of over 60 pct. The addition of Ni to the Cu-Al-Mn alloys shows a drastic effect of the formation of the strong {112}<110> recrystallization texture. Superelastic strains on the order of 7 pct., 3 times larger than those in other Cu-based shape-memory alloys (SMAs), have been realized in the textured Cu-Al-Mn-Ni alloys. The superelastic strains obtainable in the textured Cu-based SMAs are on a par with those attainable in the Ni-Ti-based alloys.
287.
Suzon, E., F. Wagner, et al. (2003). Recrystallization texture and microstructure of an ODS Fe40Al alloy. Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
The general purpose of our work is to study the mechanisms responsible for textural and microstructural evolutions during static recrystallizations in a fine grained ODS Fe-40Al alloy initially processed by extrusion of mechanically alloyed powders. The present contribution will show that despite very similar textures of the as-deformed samples, the recrystallization textures were found to be very different for 10 and 16% compression strain. A microstructure investigation also revealed that these differences in crystallographic textures were concomitant with a strong change in the morphology of the recrystallized grains.
288.
Suzuki, H., O. Izumi, et al. (1982). "Factors Affecting the Interface Sliding in Alpha-Beta-Brass 2-Phase Bicrystals." Acta Metallurgica 30(8): 1647-1654.
289.
Suzuki, K., I. Shigematsu, et al. (2005). "Influences of chip characteristics and extrusion conditions on the properties of a 6061 aluminum alloy recycled from cutting chips." Journal of Japan Institute of Light Metals 55(9): 395-399.
Possibilities of the consolidation process using hot extrusion were investigated in order to recycle the cutting chips of the aluminum alloy efficiently. Influences of the size and the cleanliness of the cutting chips and extruding conditions on mechanical properties and corrosion resistance of the recycled materials were examined to optimize the processing condition. Cutting chips were collected from 6061 aluminum alloy round bars using the lathe, and they were pretreated to prepare chips with different cleanliness. The cutting chips were forced into a pure aluminum can, and extruded under various extrusion ratios and temperatures. The obtained extrusions with T6 heat-treatment were defined as "recycled materials". Optical microscopic observation, EBSP analysis, tensile tests and immersion corrosion tests were carried out to the recycled materials. Mechanical properties and the corrosion resistance of the recycled materials were almost equivalent to the highest values of the virgin material. Higher extruding temperature was required in order to consolidate finer cutting chips. However, the recycled materials using fine chips showed improved strength parallel to the extrusion direction.
290.
Suzuki, S. (2001). "Introduction EBSP Method and its Advantages with Nano Probe Shottky FE-SEM." Materia Japan 40(7): 612-616.
291.
Svetchnikov, V. L. and V. M. Pan (2005). "Rotary relaxation at growth of thin HTSC films." Physics of Metals 27(4): 499-510.
Ways of the dislocation-nanostructure formation in epitaxial films of high-temperature superconductor YBa2Cu3O7-δ (YBCO) are studied and discussed. A calculation is performed for the dependence of a free energy of the 'film-interface-substrate' system on the rotation angle of the island of growing film with respect to substrate main axes. The film transformation from the initial elastically-deformed (pseudomorphic) state to the relaxed one is shown to be caused by arising minimum of the system free energy in a range of small angles of rotation. The analysis of the interface energy versus mismatch value gives a basis to conclude that the relaxation of the elastically-deformed film state has to occur in the most energetically beneficial mode, which is a rotation of nanovolumes with formation of the network of both interface dislocations on twisting boundaries and mismatch dislocations on tilt boundaries. Dislocation nanostructure is analysed by the transmission electron microscopy (TEM) and electron back-scattering diffraction (EBSD) data. These data evidence the formation and evolution of the subgrain dislocation nanostructure in YBCO films.
292.
Svetchnikov, V. L., H. W. Zandbergen, et al. (2004). "Mechanisms of nanostructure formation in films of a high-temperature superconductor YBa2Cu3O7- δ." Physics of Metals 26(6): 725-739.
In a given work on the basis of results of transmission electron microscopy as well as electron backscatter diffraction (EBSD) on YBa2Cu3O7-δ (YBCO) thin superconducting films, the conclusion is made with regard to the formation mechanisms and evolution of the subgrain dislocation nanostructure in the films. As shown, dislocation accumulations ('clouds' or 'forests') of very high density in very thin (a few atomic layers) YBCO films at first are located randomly at the interface. Then in thicker YBCO films, these accumulations transform into the regular low-angle sub-boundaries. The evolution of the dislocation nanostructure occurs due to the mechanism of polygonization. The nanostructure formation in the depositing YBCO films proceeds according to the diagram suggested - 'film structure - oxygen partial pressure - substrate temperature'. With this diagram, the proper regimes of the films' deposition with controlled nanostructure can be determined.
293.
Sweeney, F., C. Trager-Cowan, et al. (2001). "Electron Backscattered Diffraction Patterns from Cooled Gallium Nitride Thin Films." Physica Status Solidi A 228(2): 533-536.
The acquisition of electron backscattered diffraction (EBSD) (or Kikuchi diffraction) patterns in the scanning electron microscope is proving to be a useful technique with which to probe the structural properties of nitride thin films. In this paper we show that if a sample is cooled the patterns improve dramatically, an increase in intensity of the Kikuchi lines and a decrease in the intensity of the diffuse background is observed. Kikuchi lines from higher order planes become visible and the HOLZ rings become better defined. Such cooled patterns yield more information on the sample, particularly on non-centrosymmetric planes, from which the polarity of the nitride thin film under investigation may be deduced.
294.
Swiatnicki, W. A. and M. W. Grabski (1986). "Effect of Carbon and Chromium on Grain-Boundary Diffusional Properties in Austenitic Steels." Acta Metallurgica 34(5): 817-822.
295.
Swiatnicki, W. A. and M. W. Grabski (1988). "Effect of Distribution of Grain-Boundary Diffusivity on Plastic-Flow of Austenitic Steel.1. Characterization of Microstructure - Determining the Distribution of Grain-Boundary Diffusivity." Materials Science and Engineering 100(APR): 85-92.
296.
Swiatnicki, W. A., M. Styczynska, et al. (1985). "The Effect of Grain-Boundary Precipitation on the Stability of Extrinsic Grain-Boundary Dislocations in Austenitic Steel and Aluminum-Alloy." Acta Metallurgica 33(9): 1643-1650.
297.
Swiatnicki, W. A., M. W. Grabski, et al. (1986). "Investigation of Grain-Boundary Diffusion in Polycrystals by Means of Extrinsic Grain-Boundary Dislocations Spreading Rate." Acta Metallurgica 34(4): 599-605.
298.
Swiatnicki, W. A., S. Poulat, et al. (1998). "Thermal-Stability of Extrinsic Dislocations in Near Sigma-11 Grain-Boundaries in Nickel." Acta Materialia 46(5): 1711-1717.
Thermal stability of the extrinsic grain boundary dislocations (EGBDs) in near 11 grain boundaries (GBs) has been investigated in nickel bicrystal thin foils containing different levels of impurities. The geometrical (GB misorientation and plane-GB steps) and chemical (segregation) factors which may affect the EGBD relaxation have been considered. The results show that the EGBD accommodation kinetics depends strongly on the segregation level, related to the GB plane orientation, and on the EGBD line orientation in the GB plane. They are mainly interpreted in terms of intergranular diffusion. They support the conclusion that no geometrical criterion can predict GB behavior, particularly in presence of GB segregation.
299.
Switz, R. J. (1979). Joining I: Mechanical/Adhesive. Beryllium Science and Technology. D. R. Floyd and J. N. Lowe. New York, Plenum Press. 2: 231-247.
joining technology/techniques reviewed for Be
300.
SzabÓ, P. J. (2004). "Microstructure development of creep resistant ferritic steel during creep." Materials Science and Engineering A 387-389: 710-715.
Creep resistant steel samples were subjected to creep loading at 550 °C for different periods of lifetime in order to observe the development of the microstructure. After about 500 h, a local maximum was observed in the strain of the individual grains (monitored by electron back scattering diffraction, using the grain orientation spread and grain average misorientation parameters), after which a relaxation occurred. Based on transmission electron microscopic images, it is assumed that carbide precipitates caused pinning of the dislocations, and only after sufficient accumulation at the carbides could the dislocations move. After about 500 h, the sub-grain size increased, as well as the average distance between carbides. This caused enhanced movement of dislocations, and the slope of the creep curve increased.
301.
Szabo, P. J. (2003). Discontinuous Creep Behaviour of 15Mo3 Type Steel. 4th Hungarian Conference on Materials Science, Testing and Informatics, Balatonfured, Hungary, Trans Tech Publications.
15Mo3 type steel samples were subjected to creep loading at 550DGC in order to investigate the development of microstructure as well as the effect of the carbides. It was found that after reaching the secondary creep region, the slope of the creep curve decreased, the creep rate reached a minimum value and remained unchanged as the effect of strainhardening is counterbalanced by an annealing influence. After a short plateau, the slope increased. In order to explain this type of behaviour and to suggest a damage mechanism, TEM and EBSD investigations were performed. At the beginning of the process, subgrain formation started which was retarded by the carbides. At elevated temperature, however, the average distance between carbides increased, and the pinned dislocations were able to bypass them, the internal strain inside the grains (after reaching a maximum value after about 481 hours) decreased, and the creep process accelerated.
302.
Szabo, P. J. and I. Szalai (2003). Effect of monotonic and cyclic deformation on the IQ-maps of austenitic stainless steel. 4th Hungarian Conference on Materials Science, Testing and Informatics, Balatonfured, Hungary, Trans Tech Publications.
EBSD (electron back scattering diffraction) technique allows us to determine the crystallographic properties of crystalline materials by recording the so-called Kikuchi-lines from a certain area of the specimen. If the crystal structure is free of defects, these lines have sharp edges, but if the sample contains defects, e.g., dislocations or stacking faults, the lines show a diffuse characteristic with blurred edges. According to this, image quality maps made by scanning the sample surface and calculating the quality of Kikuchi-figures at each pixel, show the deformation state of the material. Austenitic stainless steel samples were subjected to different amount of monotonic tensile loading and different number of tensile-compressive cycles at room temperature. Image quality (IQ) map of each specimen was recorded. It was shown that the average gray-scale value of the maps follows the tendency of deformation. In case of monotonic tension, the effect of grain orientation was seen in the gray scale histogram as a fluctuation of gray scale values, while in case of cyclic deformation the cyclic softening and then hardening of the material can be seen in the IQ-maps.
303.
Sztwiertnia, K., J. Pospiech, et al. (1999). Topological aspects of the ridging phenomenon in ferritic stainless steel. Twelfth International Conference on Textures of Materials (ICOTOM 12), McGill University, Montreal, Canada, NRC Research Press.
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