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237 records found
1.
König, U. and B. Davepon (2001). "Microstructure of
polycrystalline Ti and its microelectrochemical properties by means of
electron-backscattering diffraction (EBSD)." Electrochimica Acta
47: 149-160.
The electrochemical behaviour of polycrystalline materials is determined
usually by grain orientations. The correlation between crystallographic
orientation and electrochemical behaviour is examined on titanium as example
by combining microelectrochemical techniques with orientation measurements
carried out with electron-backscattering diffraction (EBSD). The results
will be compared with former experiments in which crystallographic data were
analysed with anisotropy microellipsometry (AME). Whereas AME is only
capable to determine a single Euler angle F, EBSD analysis reveals all three Euler angles.
For a clear crystallographic determination of the metal surface on hexagonal
titanium, it is sufficient to determine the Euler angles F and φ2. The angle
φ1 can be neglected. For F
< 45°, the angle φ2 has an almost negligible influence
on the electrochemical behaviour. The oxide layer thickness can be
characterised by the analysis of the EBSD pattern quality. Due to the fact
that oxide films on different titanium grains show different interference
colours, it is possible to correlate interference colours of oxide films
formed at U=15 V with the crystallographic orientation of the underlying
grains which have been determined by EBSD orientation mapping. With the help
of this orientation/colour correlation, the grain orientations can be
estimated quickly with a microscope.
2.
Kaczmarek, D. (2001). "Investigation of
Surface-Topography Using a Multidetector System in a SEM." Vacuum
62(2-3): 303-308.
3.
Kaibara, K., K. Tanaka, et al. (2004). Grain size and orientation analysis
of SrBi2(Ta,Nb)2O9 films by electron
backscatter diffraction. International Meeting for Future of Electron
Devices, Kansai, Kyoto, Japan, IEEE.
The orientation of polycrystalline ferroelectric films used in ferroelectric
random access memories (FeRAMs) has a significant influence on the
electrical properties. In particular, the polarization of ferroelectric
SrBi2Ta2O9 (SBT) and
SrBi2(Ta,Nb)2O9 (SBTN) films strongly
depends on the crystal orientation because these films polarize only along
the a-axis as stated in Y. Shimakawa et al. (1999), For instance, an x-ray
diffraction measurement indicated that an SBT film deposited on an
(111)-oriented platinum plate tends to preferentially grow along the c-axis
as the average grain size increases as presented in C. Bae et al. (1999). In
view of the scaling limit of FeRAMs governed by the grain size, it is
crucial to obtain information on whether the entire film is oriented along
the c-axis preferentially or c-axis-oriented grains have grown exclusively.
We have investigated the relationship between the grain size and the crystal
orientation of individual grains of SBTN films, for the first time, via
electron backscatter diffraction (EBSD) technique as presented in A. J.
Schwartz et al. (2000) and B. L. Adamus et al. (1993).
4.
Kaibyshev, O. A., N. K. Tsenev, et al. (1984). "Influence of the
Grain-Boundary State on the Superplastic Flow." Doklady Akademii Nauk
SSSR 278(1): 93-97.
5.
Kaibyshev, R. and I. Mazurina (2004). Mechanisms of Grain Refinement in
Aluminum Alloys during Severe Plastic Deformation. Second Joint
International Conference on Recrystallization and Grain Growth, ReX &
GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
The mechanisms of grain refinement during severe plastic deformation have
been studied, by comparing the microstructure evolution in an AA2219
aluminium alloy, containing Al3Zr nanoscale particles, with that in a dilute
Al-3%Cu alloy deformed identically by equal-channel angular extrusion (ECAE)
at 250 deg C to a maximum strain of approx12. Transmission electron
microscopy (TEM) was used on the AA2219 alloy to reveal the misorientations
of deformation-induced boundaries. Microstructural evolution in the Al-3%Cu
alloy was studied by electron-back scattering diffraction (EBSD) orientation
mapping. It was shown that the mechanism of grain refinement in the AA2219
alloy is continuous dynamic recrystallization (CDRX) consisting of two main
elementary processes. In the initial stages of plastic deformation, the
formation of three-dimensional arrays of low-angle boundaries (LABs) takes
place. Further strain results in increasing misorientation of these
boundaries providing their gradual transformation into high-angle boundaries
(HABs). A fully recrystallized structure with an average grain size of
approx0.9 mu m is evolved after a total strain of approx12. In the dilute
Al-Cu alloy the evolution of ultrafine grains with an average size of approx
6 mu m is attributed to the formation of deformation bands outlined by HABs
and extended medium to high-angle boundaries at moderate strains. The
subdivision of these deformation bands into fine grains rarely occurs
through the mechanism of geometric recrystallization (GRX). In this alloy
the main contribution in the grain refinement gives CDRX occurring within
fibrous structural features. At epsilon approx12, a partially recrystallized
structure is formed in the Al-3%Cu alloy.
6.
Kaibyshev, R., I. Mazurina, et al. (2004). Geometric Dynamic
Recrystallization in an AA2219 Alloy Deformed to Large Strains at an
Elevated Temperature. Second Joint International Conference on
Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France,
Trans Tech Publications Ltd.
The mechanism of new grain evolution during equal channel angular extrusion
(ECAE) up to a total strain of ~12 in an Al-Cu-Mn-Zr alloy at a temperature
of 475°C (0.75Tm) was examined. It was shown that the new
grains with an average size of about 15 µm result from a specific
process of geometric dynamic recrystallization (GRX) which can be considered
as a type of continuous dynamic recrystallization (CDRX). This process
involves three elementary mechanisms. At moderate strains, extensive
elongation of initial grains takes place; old grain boundaries become
progressively serrated. Upon further ECAE processing, transverse low-angle
boundaries (LABs) with misorientation ranging from 5 to15° are evolved
between grain boundary irregularities subdividing the intial elongated
grains on crystallites with essentially equiaxed shape. The misorientation
of these transverse sub-boundaries rapidly increases with increasing strain,
resulting in the formation of true recrystallized grains outlined by
high-angle boundaries (HABs) from all sides. In the same time, the average
misorientation of deformation induced boundaries remains essentially
unchanged during ECAE. It is caussed by the fact that the evolution of LABS
with misorientation less than 4° occurs continuously during severe
plastic deformation. The mechanism maintaining the stability of the
transverse sub-boundaries that is a prerequisite condition for their further
transformatioin into HABs is discussed.
7.
Kaibyshev, R., K. Shipilova, et al. (2005). "Continuous dynamic
recrystallization in an Al-Li-Mg-Sc alloy during equal-channel angular
extrusion." Materials Science and Engineering A 396(1-2):
341-351.
An Al-Li-Mg-Sc alloy with an initial grain size of.60 mum was processed by
equal-channel angular extrusion (ECAE) at 300 deg C up to a total strain of
12. Transmission electron microscopy (TEM) and orientation imaging
microscopy (OIM) were employed to establish the mechanism of grain
refinement. It was found that new ultrafine grains evolved by a
strain-induced continuous process, which is termed continuous dynamic
recrystallization (CDRX). At epsilon.1, a well-defined subgrain structure
had developed. Upon further straining the average mis-orientation of
deformation-induced boundaries increased; low-angle boundaries (LAB)
gradually converted into true high-angle boundaries (> or = 15DG) (HAB).
At epsilon.4, arrays of boundaries with low and high angle mis-orientations
were observed. At epsilon. 12, a structure dominated by HAB with an average
grain size of.0.9 mm was formed. This size is roughly similar to that for
subgrains developed at preceding strains. It was shown that CDRX occurs
homogeneously; the formation of new grains takes place both along initial
boundaries and within interiors of original grains as well.
8.
Kain, V., P. Sengupta, et al. (2005). "Case Reviews on the Effect of
Microstructure on the Corrosion Behavior of Austenitic Alloys for Processing
and Storage of Nuclear Waste." Metallurgical and Materials Transactions
A 36A(5): 1075-1084.
This article describes the corrosion behavior of special austenitic alloys
for waste management applications. The special stainless steels have
controlled levels of alloying and impurity elements and inclusion levels. It
is shown that "active" inclusions and segregation of chromium
along flow lines accelerated IGC of nonsensitized stainless steels.
Concentration of Cr+6 ions in the grooves of dissolved inclusions increased
the potential to the transpassive region of the material, leading to
accelerated attack. It is shown that a combination of cold working and
controlled solution annealing resulted in a microstructure that resisted
corrosion even after a sensitization heat treatment. This imparted extra
resistance to corrosion by increasing the fraction of "random"
grain boundaries above a threshold value. Randomization of grain boundaries
made the stainless steels resistant to sensitization, IGC, and intergranular
stress corrosion cracking (IGSCC) in even hot chloride environments. The
increased corrosion resistance has been attributed to connectivity of random
grain boundaries. The reaction mechanism between the molten glass and the
material for process pot, alloy 690, during the vitrification process has
been shown to result in depletion of chromium from the reacting surfaces. A
comparison is drawn between the electrochemical behavior of alloys 33 and 22
in 1 M HCl at 65 °C. It is shown that a secondary phase formed during
welding of alloy 33 impaired corrosion properties in the HCl environment.
9.
Kajihara, K., K. Tokuda, et al. (2002). Development of Cube Texture during
Industrial Processing of High Purity Aluminum Foil Obtained with 99% Volume
Fraction of Cube Component. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
The formation behavior of cube texture during industrial process in high
purity aluminum foil obtained 99% in volume fraction of Cube component was
investigated. The Cube-oriented grains after the intermediate annealing were
preferentially located in the C- and S-oriented fine microstructure, and
were also observed less in the Brass-oriented coarse bands of the
cold-rolled foils. Furthermore the fine microstructure bands and the
strong-fiber texture of hot rolled material were the origin of the high
density of Cube gains after the intermediate annealing. It is extremely
important to control and to stabilize fine grain size and strong rolling
textures of hot rolled material in order to obtain the volume fraction
greater than 99% of Cube component in the final foil.
10.
Kalidindi, S. R., A. Bhattacharyya, et al. (2003). "How do
polycrystalline materials deform plastically?" Advanced Materials
15(16): 1345-1348.
11.
Kalidindi, S. R., A. Bhattacharyya, et al. (2004). "Detailed analyses
of grain-scale plastic deformation in columnar polycrystalline aluminium
using orientation image mapping and crystal plasticity models."
Proceedings of The Royal Society of London Series A 460(2047):
1935-1956.
Deformation studies at grain level have been performed in order to model how
individual crystals in a polycrystalline material deform. The experiment was
carried out by plane-strain compression of a high-purity polycrystalline
aluminium with columnar grain structure with near <100> fibre texture
parallel to the constrained direction in the channel die. This structure was
chosen to allow a fully three-dimensional characterization of the grain
structure. The grain orientations were mapped by orientation image
microscopy, as the directionally solidified material was deformed in steps
of 10% to a total height reduction of 40%. The grains were found either to
show nearly uniform rotations or to split into two types of deformation
bands, either with repeating orientation fields or with non-repeating
orientation fields. The Taylor model and the finite-element method (FEM)
were, as usual, quite successful in predicting the average deformation
texture, but the Taylor model failed totally to predict the rotation of
individual grains. The FEM was more successful in predicting the individual
grain rotations but did not, as in a previous study, predict the morphology
of the deformation bands. The significant discovery, made here, was that it
appeared possible to model the local deformation at a grain scale, from the
observed individual deviations of the grain rotations from those predicted
if each grain underwent just the plane-strain conditions imposed on the
sample. Plastic work rates were computed allowing four shears (two shears in
each of the two contact planes) that are compatible with the channel-die
geometry. It was found that in all the 'hard' grains (those with high Taylor
factors), the additional shears (in type and magnitude) that minimized the
plastic energy dissipation rate were the same shears that were needed to
match the observed grain rotations. Adjacent Taylor 'soft' grains were found
to have been subjected to the additional shears imposed by their
neighbouring hard grains. This was true even when these shears raised the
plastic work of the soft grains. This effect was most marked when the soft
grains were small in size. These additional shears found by this plastic
work analysis were consistent with the observed additional shear seen in the
overall shape change of the sample. The grains forming non-repeating
orientation fields had low initial Taylor factors and were surrounded by
high-Taylor-factor grains, usually of larger size, but which had adopted
somewhat different extra shears. The grains showing repeating orientation
fields were found to have an orientation, near 'cube' (001) (100), which was
initially unstable leading to a break-up into different orientation fields
when deformed. These differing deformation bands in the cube grains followed
different strain paths, which also minimized their plastic work.
12.
Kalu, P. N., A. D. Rollett, et al. (2005). "The role of orientation
pinning in statically recrystallized oxygen-free high-conductivity copper
wire." Metallurgical and Materials Transactions A 36A(1):
205-215.
The role of orientation pinning by neighboring grains on migrating
boundaries in a statically recrystallized oxygen-free high-conductivity
(OFHC) copper was investigated. Two specimens of heavily drawn OFHC copper
wires deformed to true strains of 2.31 and 3.56 were annealed at 170
operties C and local orientations were mapped by means of the automated
electron backscattered diffraction technique. Inverse pole figures,
misorientation distribution functions, and grain boundary misorientations
were calculated from local orientation data. In spite of annealing, the
microstructure of the low-strain specimen was characterized by elongated
grains, similar to the as-deformed structure, whereas the microstructure of
the high-strain specimen showed a high fraction of well-defined
recrystallized grains. The recrystallized grains consisted of type A grains,
which mostly grew laterally with {hkl} <100 > orientations, and type B
grains, which generally grew axially with {hkl} <111> orientations.
Type A grains were larger and of higher frequency than type B grains. The
large size of Type A grains was attributed to the high frequency of the
mobile boundaries with misorientations in the 40 to 50 deg range. Boundaries
that were misoriented at 60 deg <111> (Σ3) were found to exert
the greatest pinning effect on the growing grains. This caused
recrystallized grains to grow either laterally or axially, and sometime led
to "branching." A detailed analysis of the influence of the next
neighbor misorientations in the perimeter of the recrystallized grains is
presented.
13.
Kalu, P., D. R. Waryoba, et al. (2000). "Restoration Mechanisms in
Highly Deformed Cu-based Conductor Wires." IEEE Transactions On Applied
Superconductivity 10(1): 1296-1299.
14.
Kamaya, M., A. J. Wilkinson, et al. (2005). "Measurement of plastic
strain of polycrystalline material by electron backscatter
diffraction." Nuclear Engineering and Design 235(6):
713-725.
It is important to know the degree of plastic strain in order to evaluate
the susceptibility and crack growth rate of stress corrosion cracking (SCC)
in stainless steel and nickel based alloy, because SCC is enhanced by the
cold work and causes many problems in nuclear power plant components. In
this study, electron backscatter diffraction in conjunction with scanning
electron microscopy is applied to measure the plastic strain imposed to
stainless steel by tensile load. A new parameter, which quantifies the
spread of the crystal orientation within individual grains arising due to
dislocation accumulation during plastic deformation, is correlated with
imposed plastic strain. The new parameter is called 'crystal deformation'
and is determined from the spread in misorientation from the central grain
orientation. It is confirmed that this parameter has a good correlation with
plastic strain and is not affected by the data density of the crystal
orientation map. The dislocation density distribution is also evaluated from
the misorientation from the central orientation. Relatively high dislocation
density was observed near grain boundaries and grain boundary triple points,
which was consistent with the observed deterioration of EBSD pattern quality
in those locations.
15.
Kamaya, M., A. J. Wilkinson, et al. (2006). "Quantification of plastic
strain of stainless steel and nickel alloy by electron backscatter
diffraction." Acta Materialia 54(2): 539-548.
Electron backscatter diffraction (EBSD) in conjunction with scanning
electron microscopy is applied to assess the plastic strain present in
stainless steel and nickel alloys following tensile loading. A parameter,
which quantifies the spread of the crystal orientation within individual
grains arising due to dislocation accumulation during plastic deformation,
is correlated with imposed plastic strain. The parameter is called the
‘modified crystal deformation’ and is determined from the spread
in misorientation from the central grain orientation. It was confirmed that
the parameter has a good correlation to the degree of the plastic strain and
is independent of the measurement conditions such as the EBSD system used
for the measurement, number of data and step size in the crystal orientation
map, electron beam condition, grain size and material.
16.
Kamikawa, N., N. Tsuji, et al. (2004). "Microstructure and texture
through thickness of ultralow carbon IF steel sheet severely deformed by
accumulative roll-bonding." Science and Technology of Advanced
Materials 5(1-2): 163-172.
Ultralow carbon interstitial free (IF) steel was severely deformed up to a
strain of 5.6 by the Accumulative Roll-bonding (ARB) process at 773 K.
Crystallographic analysis by electron back-scattering diffraction (EBSD)
technique in a field-emission type scanning electron microscope (FE-SEM) was
carried out for the ARB processed IF steel throughout thickness of the
sheet. Microstructural parameters, such as grain size, grain boundary
misorientation and crystal orientation, through thickness of the ARB
processed specimen were quantitatively clarified by the EBSD analysis. The
ARB processed material was homogeneously filled with the lamellar or
pancake-shaped ultrafine grains whose mean grain thickness were about
200-300 nm. More than 80 percent of the boundaries surrounding the ultrafine
grains were high-angle grain boundaries. The ARB processed sheet had unique
and complex textural distribution through thickness. The region near the
thickness center has the conventional but quite weak rolling texture mainly
composed of <110>//RD and <111>//ND. On the other hand, the
surface region had the sharp shear texture,ND//<110>. Such a textural
distribution is due to the redundant shear strain induced by high-friction
between the sheet and roll during rolling. The correspondence between the
textural and microstructural distribution and the shear strain distribution
throughout thickness of the sheet was discussed.
17.
Kamikawa, N., X. Huang, et al. (2004). EBSD and TEM Characterization of
Ultrafine Grained High Purity Aluminium Produced by Accumulative
Roll-Bonding. Materials Science Forum, Osaka, Japan.
18.
Kaneko, Y., K. Fukui, et al. (2005). "Electron channeling contrast
imaging of dislocation structures in fatigued austenitic stainless
steels." Materials Science and Engineering A 400-401:
413-417.
Dislocation structures of fatigued austenitic stainless steel polycrystals
were analyzed by electron channelling contrast imaging. The formation of
persistent slip bands (PSBs) and vein structures were recognized in some
grains. Effects of both grain size and Schmid factor on the PSB formation
were investigated. The average diameter of the grains containing PSBs was
higher than that without PSBs. On the other hand, there was no significant
difference in the average Schmid factor between the grains with PSBs and the
other grains. PSB formations was detected even in grains, where the Schmid
factor was low, and the grain diameter was small. It was proposed that the
stress concentration coming from piled-up dislocations in a neighboring
grain was one of the reasons for the PSB formation in such grains.
19.
Kaneno, Y. and T. Takasugi (2003). "Grain Boundary Character
Distribution in Recrystallized L12 Ordered Intermetallic
Alloys." Metallurgical and Materials Transactions A 34A(11):
2429-2439.
The grain-boundary character distribution (GBCD) of cold-rolled and
subsequently recrystallized Co3Ti and Ni3(Si,Ti)
ordered alloys with an L12 structure was studied by the electron
backscattered diffraction method, in association with texture. For
comparison the GBCD of recrystallized pure copper and aluminum was also
determined. The recrystallization textures of the Co3Ti alloys as
well as the Ni3(Si,Ti) alloy were significantly weak and
different from those of the pure copper and aluminum with a strong cube
texture. The GBCD of the Co3Ti alloys was charecterized by a high
frequency of Σ3 boundaries. On the other hand, the GBCD of the
Ni3(Si,Ti) alloy was characterizied by a lower frequency of S3
and a higher frequency of random (e.g. Σ>29) boundaries than that
of the C3Ti alloys. However, the GBCD of the Co3Ti and
Ni3(Si,Ti) were similar to each other and also quite similar to
those of the pure copper and aluminum, when Σ3 boundaries are excluded
from the GBCD. Based on these results, the formation mechanism responsible
for the recrystallization textures and the grain-boundary structure and
energy of the Co3Ti and Ni3(Si,Ti) were discussed, in
comparison with those of pure copper and aluminum.
20.
Kaneno, Y. and T. Takasugi (2004). Characterization of Grain Boundaries in
Recrystallized L12-Type Intermetallic Alloys. Proceedings of the
International Conference on New Frontiers of Process Science and Engineering
in Advanced Materials - The 14th Iketani Conference, Kyoto, Japan.
Microstructural feature of the recrystallized Co-based (Co3Ti)
and Ni-based (Ni3(Si,Ti) and Ni3Fe) ordered alloys
with L12 structure was investigated by the electron backscatter
diffraction (EBSD) method, with emphasis on grain boundary character
distribution (GBCD). For comparison, the GBCDs of the recrystallized Co-Ni,
Ni-Fe and 70/30 brass disordered alloys, and also copper, nickel and
aluminum pure metals with Al (fcc) structure, which have widely different
stacking fault energies, were also determined. The frequency of Σ3
boundary for the Co-based alloys was higher than that for the Ni-based
alloys, regardless of ordered L12 alloy or disordered fcc alloy,
indicating that the frequency of Σ3 boundary was primarily dominated
by stacking fault energy. Furthermore, the effect of ordering energy on
structure and energy of the grain boundaries including Σ3 boundary in
the ordered L12 alloys was discussed.
21.
Kaneno, Y. and T. Takasugi (2005). "Effects of stacking fault energy
and ordering energy on grain boundary character distribution of
recrystallized L12-type ordered alloys." Materials Science
and Engineering A 393(1-2): 71-79.
Microstructural feature of the recrystallized Co-based (Co3Ti)
and Ni-based (Ni3(Si,Ti) and Ni3Fe) ordered alloys
with L12 structure was investigated by the electron backscatter
diffraction (EBSD) method with emphasis on grain boundary character
distribution (GBCD). For comparison, the GBCDs of the recrystallized Co-Ni,
Ni-Fe and 70/30 brass disordered alloys, and also copper, nickel and
aluminum pure metals with A1 (fcc) structure, which have widely different
stacking fault energies, were also determined. The frequency of Σ3
boundary for the Co-based alloys is higher than that for the Ni-based
alloys, regardless of ordered L12 alloy or disordered fcc alloy,
indicating that the frequency of Σ3 boundary is primarily dominated by
stacking fault energy. Furthermore, the effect of ordering energy on
microstructure and energy of the grain boundaries, including Σ3
boundary in the ordered L12 alloys is discussed. Copyright 2004
Elsevier B.V. All rights reserved.
22.
Kang, J. Y., S. H. Kang, et al. (2005). Texture analysis on diamond
particles in a high pressure-high temperature reaction cell. International
symposium on research reactor and neutron science, Taejon. Korea, KAERI,
Taejon (Korea, Republic of).
An attempt to measure the orientation distribution of diamond particles
synthesized in a composite cell by High Pressure-High Temperature (HPHT)
process was carried out. The structural information of the phases
constituting the cell was obtained by neutron High Resolution Powder
Diffractometer (HRPD) including a crude textural information from the
measurements at different sample orientations. And the orientation
distribution of diamonds was Evaluated by electron BackScattered Diffraction
(EBSD). The diamond particles exhibited nearly random nature in orientation
distribution but a little tendency to align <111> axes parallel to the
compression axis was detected due to the orientation relationship in
nucleation or preferential arrangement of interface planes during growth.
23.
Kang, J., D. S. Wilkinson, et al. (2006). "On the sequence of
inhomogeneous deformation processes occurring during tensile deformation of
strip cast AA5754." Acta Materialia 54(1): 209-218.
A variety of surface observational techniques including full-field strain
mapping based on digital image correlation analysis, electron back-scatter
diffraction and in situ field emission scanning electron microscopy have
been used to follow the patterns of inhomogeneous flow which occur during
tensile testing of AA5754. The observations permit the relationships between
slip lines, dynamic strain aging, shear localization, diffuse and localized
necking to be delineated. In addition, fracture observation and
metallographic assessment of damage processes have been conducted to enable
an understanding of the relationship between inhomogeneous deformation and
ductility to be developed.
24.
Kang, J.-H. and H.-C. Lee (2004). "The Orientation Distribution of
Ferrite Grains Dynamically and Statically Transformed from Heavily Deformed
Austenite." Materials Transactions 45(7): 2219-2223.
The orientation distribution of ferrite grains formed by dynamic and static
transformation was examined using the electron backscattered diffraction
technique. The orientation of ferrite grains, transformed both dynamically
and statically from deformed austenite, showed a large deviation from the
Kurdjumov-Sachs (K-S) orientation relationship. The deformed austenite grain
structure modeled using Ni-30Fe alloy showed inhomogeneous and localized
deformations within the austenite grains. A large orientation variation was
observed across this localized deformation zone, and the large deviation of
the ferrite orientation from the K-S relationship was attributed to the
nucleation of ferrite from this localized deformation region. A low carbon
steel with a chemical composition of 0.14C-0.24Si-1.2Mn-0.0033B-0.012Ti was
used in this experiment.
25.
Kang, J.-H., D.-W. Suh, et al. (2003). "Effect of external stress on
the orientation distribution of ferrite." Scripta Materialia
48(1): 91-95.
The effect of external stress on the orientation distribution of ferrite
during the transformation was examined. Two types of carbon steel were used
to evaluate the deviation angle of ferrite from the Kurdjumov-Sachs (K-S)
relationship using electron backscattered diffraction The K-S relationship
was weakened when an external stress was applied during the
transformation.
26.
Kang, J.-Y., D.-I. Kim, et al. (2004). Orientation Spread in Deformed Grains
and Its Relevance to Recrystallization Texture Development in IF Steels.
Second Joint International Conference on Recrystallization and Grain Growth,
ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
Deformation characteristics of cold rolled grains and their contribution to
the development of recrystallization texture in IF steel were investigated
using EBSD Quantitative evaluation of the intra-granular orientation spread
in the deformed grains was attempted. Both of the GAM and SGS could
represent the orientation spread but in different manner. The GAM value was
higher in {111}//ND orientations than in other orientation groups implying
steep orientation gradient within short ranges in {111}//ND oriented grains.
This steep orientation gradient was generally originated from the existence
of deformation heterogeneities. Particularly, {111}<112> orientation
which was the dominant component in the recrystallization texture showed the
maximum values of both GAM and SGS, which was caused by the frequent
development of shear bands. SGS values of {001}//ND oriented soft grains
were unexpectedly large in spite of their small GAM values. It could be
confirmed that their uniform deformation behavior led to the gentle but
monotonous orientation gradient in long ranges. The lowest values of both
GAM and SGS were obtained in the {112}<110> orientation, probably,
because of the highest orientation stability in that orientation during
plain strain deformation condition. GAM was more closely related to the
development of recrystallization texture and the significance of the steep
orientation gradient in the recrystallization behavior should be
re-addressed.
27.
Kang, J.-Y., S. H. Kang, et al. (2004). "Orientation distributions of
diamond particles in polycrystalline diamond synthetic cells." JOM
56(11): 148.
The orientation distributions of diamonds in two types of synthetic cells
were examined. From the orientation distribution function (ODF) calculated
from EBSD data, it was concluded that the diamonds in layered cell exhibited
weak texture of <111> parallel to the stacking direction. And from the
neutron diffraction spectrum of powdered cell, the texture indices of
diamond 111, 220 and 311 planes were calculated as 1.18, 0.89 and 0.90,
respectively, which implied that the orientation distribution of the
diamonds approached random distribution. In layered cell, there exists
concentration gradient of carbon around growing diamonds along the stacking
direction. By contrast, in powdered cell, diamonds are surrounded by
homogeneous carbon solution. This discrepancy was considered to lead to the
different orientation distributions of diamonds in the two cells. The
favored alignment of 111 planes perpendicular to the stacking direction in
layered cell was thought to originate from their lowest surface energy.
28.
Kang, J.-Y., S.-Y. Lee, et al. (2003). Rapid grain growth of hot extruded
Al-Zn-Mg-Cu-(Sc) alloy during heat treatment. Designing, Processing and
Properties of Advanced Engineering Materials: Proceedings on the 3rd
International Symposium on Designing, Processing and Properties of Advanced
Engineering Materials, Jeju Island, South Korea.
Rapid grain growth and artificial aging characteristics during heat
treatment is investigated for hot extruded Al-Zn-Mg-Cu-(Sc) alloys. Two
Al-0.1wt%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 120n formed 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.
29.
Kang, S. H., H. S. Jung, et al. (2005). High Tensile Strength of Drawn Gold.
Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech
Publications.
This paper studies the microstructure of drawn gold wires to equivalent
strain of 10 and to equivalent strain of 8.5 then heat-treated. The texture
of gold wire drawn to strain of 10 is mainly composed of <100> and
<111> fibers. Tensile strength of the gold wire increases with
<111> fiber fraction, while the grain size does not appear to affect
the tensile property. With an exception at heat treatment at 600°C, the
texture of gold wire drawn the strain of 8.5 is replaced with <100>
fiber component by heat treatment process at 400~700°C. Heat treatment
at 600°C produces <110> fiber or <112> fiber, depending upon
annealing time.
30.
Kang, S. H., H. S. Jung, et al. (2005). High Tensile Strength of Drawn Gold.
Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech
Publications.
This paper studies the microstructure of drawn gold wires to equivalent
strain of 10 and to equivalent strain of 8.5 then heat-treated. The texture
of gold wire drawn to strain of 10 is mainly composed of <100> and
<111> fibers. Tensile strength of the gold wire increases with
<111> fiber fraction, while the grain size does not appear to affect
the tensile property. With an exception at heat treatment at 600°C, the
texture of gold wire drawn the strain of 8.5 is replaced with <100>
fiber component by heat treatment process at 400~700°C. Heat treatment
at 600°C produces <110> fiber or <112> fiber, depending upon
annealing time.
31.
Kang, S. H., W. H. Bang, et al. (2005). Microtexture Analysis of Friction
Stir Welded Al 6061-T651 Plates. Textures of Materials - ICOTOM 14, Leuven,
Belgium, Trans Tech Publications.
Microstructural characteristics of friction-stir-welded Al 6061-T651 with
varying rotating and advancing speed were examined by the electron
backscattering diffraction (EBSD) installed in field emission-scanning
electron microscopy (FE-SEM). It was found that FSW produced an equiaxed
fine-grained microstructure in weld zone and the grain size in weld zone
decreased up to about 4~6 μm with decreasing rotating speed. The
primary textures developed in weld zone were {100}<001>,
{110}<001> and {111}<110>. In thermo-mechanical affected zone,
the change in grain size was not significant, however, large number of low
angle grain boundaries were observed, which seems to be concerned with the
formation of subgrains due to the development of dislocation cells.
32.
Kang, S. S. and I. S. Kim (1992). "Dynamic Strain-Aging Effect on
Fracture-Toughness of Vessel Steels." Nuclear Technology 97(3):
336-343.
33.
Kang, S.-b., B.-K. Min, et al. (2005). "Effect of Asymmetric Rolling on
the Texture and Mechanical Properties of AA6111-Aluminum Sheet."
Metallurgical and Materials Transactions A 36A(11):
3141-3149.
Aluminum-alloy sheets are considered to be one of the high-potential
substitutes for steel sheets, when considering the weight reduction of
automobiles. However, aluminum-alloy sheets have inferior formability,
mainly due to their lower plastic-strain ratios. The plastic-strain ratios
of aluminum-alloy sheets can be increased with the formation of
shear-deformation texture through the sheet thickness. Asymmetric rolling,
in which the circumferential velocities of working rolls are different, is a
favorable process for imposing shear-deformation texture through the sheet
thickness. In this study, commercial AA6111-alloy sheets were used to
compare the effects of conventional symmetric rolling and asymmetric rolling
in controlling the shear textures and grain refinement, as well as the
mechanical properties of the tensile and plastic-strain ratio.
34.
Kang, Y., H. Ren, et al. (2005). "Carbon diffusion in hot strips of low
carbon steel produced by CSP line under different thermal histories."
Journal of Materials Science and Technology 21(1): 21-24.
Two experiments were carried out on the same compact strip production (CSP)
line, which differs in that one of them experienced γ→
α→γ* thermal history. The differences in
microstructure, precipitation, misorientation etc between two experiments
were investigated by using scanning electron microscopy (SEM), transmission
electron microscopy (TEM), electron back-scattered diffraction (EBSD) and
positron annihilation technique (PAT). The carbon concentration in matrix is
more inhomogeneous in the experiment than that with
γ→α→γ* thermal history. The specific
precipitation characteristic in the experiment without
γ→α→γ* thermal history is discussed on
the basis of different carbon diffusion behavior and interaction between
dislocation and excess carbon.
35.
Kantrakova, D., C. Maas, et al. (1998). "Experiences on Contrasting
Microstructure Using Orientation Imaging Microscopy." Praktische
Metallographie 35: 4-20.
Orientation Imaging MicroscopyTM is one of the common terms for the analysis
of three-dimensional intensity distribution of backscattered electrons in
the Scanning Electron Microscope. This three-dimensional intensity
distribution (Kikuchi Pattern) is determined by the crystal lattice and its
orientation in the irradiated region of the sample. During the scanning of
the sample by the electron beam, every step of scan gives information about
the crystal lattice and its orientation. Analagous to Polarization Light
Microscopy, a contrast within the polished sample surface can be obtained as
all adjacent scanning points of uniform orientation belong to the same
grain. Local changes of orientation suggest the identification of a grain
boundary.
36.
Kaouache, B., S. Berveiller, et al. (2004). "Stress analysis of
martensitic transformation in Cu–Al–Be polycrystalline and
single-crystalline shape memory alloy." Materials Science and
Engineering A 378(1-2): 232-237.
The aim of this study is to analyze the martensitic transformation in a
shape memory alloy during a superelastic loading, focusing on internal
strains, stresses and phases fractions. The behavior of the austenite phase
is studied by X-ray diffraction stress analysis during in situ tensile test
at room temperature. Both single-crystal and polycrystal samples have been
investigated. The results are discussed with the aim to correlate the
microstructural variations with the local stress state evolution in the
austenitic phase while variants of martensite form and develop during a
superelastic loading.
37.
Kapoor, K., S. V. R. Rao, et al. (2003). "Texture Measurement in
Zr-2.5%Nb Pressure Tubes for Pressurized Heavy Water Reactors." Journal
of Testing and Evaluation 31(1): 1-10.
Preferred orientation or crystallographic texture of Zr-2.5%Nb pressure
tubes for a pressurized heavy water reactor (PHWR) affects all the critical
in-reactor properties. The preferred orientation has to be measured to
standardize the process route for getting the desired in-reactor properties.
The quantitative determination involves determination of the complete pole
figure and calculation of Kearns parameters from the pole figure data.
Independently, neither the X-ray reflection nor the X-ray transmission
technique can provide the full pole figure data. The literature reports only
partial pole figures. Quantification of texture based on partial pole
figures may lead to errors in estimation. For a complete pole figure
determination, it is required to merge the data from both the reflection and
the transmission techniques. This requires a special test setup that can
combine the pole figure data obtained from the two techniques. In this
paper, a methodology for determination of the complete pole figure with
quantitative texture parameters for Zr- 2.5%Nb pressure tubes is
reported.
38.
Kar, S. K. (2005). "Modeling of mechanical properties in
alpha/beta-titanium alloys." 3387 (252 pgs).
The accelerated insertion of titanium alloys in component application
requires the development of predictive capabilities for various aspects of
their behavior, for example, phase stability, microstructural evolution and
property-microstructure relationships over a wide range of length and time
scales. In this presentation some navel aspects of property-microstructure
relationships and microstructural evolution in α/β Ti alloys will
be discussed. Neural Network (NN) Models based on a Bayesian framework have
been developed to predict the mechanical properties of α/β Ti
alloys. The development of such rules-based model requires the population of
extensive databases, which in the present case are microstructurally-based.
The steps involved in database development include producing controlled
variations of the microstructure using novel approaches to heat-treatments,
the use of standardized stereology protocols to characterize and quantify
microstructural features rapidly, and mechanical testing of the heat-treated
specimens. These databases have been used to train and test NN Models for
prediction of mechanical properties. In addition, these models have been
used to identify the influence of individual microstructural features on the
mechanical properties, consequently guiding the efforts towards development
of more robust mechanistically based models. In order to understand the
property-microstructure relationships, a detailed understanding of
microstructure evolution is imperative. The crystallography of the
microstructure developing as a result of the solid-state β →
β+α transformation has been studied in detail by employing
Scanning Electron Microscopy (SEM), Orientation Imaging Microscopy (in a
high resolution SEM), site-specific TEM sample preparation using focused ion
beam, and TEM based techniques. The influence of variant selection on the
evolution of microstructure will be specifically addressed.
39.
Kar, S., R. Banerjee, et al. (2005). Influence of Crystallographic Variant
Selection on Microstructure Evolution in Titanium Alloys. Solid to Solid
Phase Transformations in Inorganic Materials 2005, Phoenix, Arizona, USA,
TMS.
The solid state β to β+α transformation in titanium alloys
leads to rather intereesting microstructures with features spanning across a
range of length scales. Consequently, in order to understand the
property-microstructure relationships in these alloys, a detailed
understanding of microstructural evolution is imperative. A series of
controlled heat treatments have been performed on a/b titanium alloys with
the objective of arresting the microstructure at successive stages of
development. The crystallography of the microstructure has been studied in
detail by employing orientation imaging microscopy (in a high resolution
SEM). The influence of variant selection on the evolution of microstructure
and the resulting development of the colony (clustering of the same variant)
and basketweave (clustering of multiple variants) microstructures in these
alloys will be specifically addressed in this presentation.
40.
Karadge, M., X. Zhao, et al. (2006). "Microtexture of the thermally
grown alumina in commercial thermal barrier coatings." Scripta
Materialia 54(4): 639-644.
Microtextures of the thermally grown α-alumina (TGO) in isothermally
treated and thermal cycled electron beam physical vapor deposited thermal
barrier coatings (EB-PVD-TBC) and isothermally treated air plasma sprayed
(APS-TBC) specimens were studied by high resolution electron back-scattered
diffraction. The TGO in EB-PVD specimens exhibited a basal microtexture. The
TGO in APS specimens, however, did not show any significant microtexture
development.
41.
Karaman, I., H. Sehitoglu, et al. (1998). "Stress-State Effects on the
Stress-Induced Martensitic-Transformation of Carburized 4320-Steel."
Metallurgical and Materials Transactions A 29(2): 427-437.
42.
Karaman, I., H. Sehitoglu, et al. (2002). "The Deformation of
Low-Stacking-Fault-Energy Austenitic Steels." JOM 54(7):
31-37.
43.
Karato, S., S. Zhang, et al. (1998). "Experimental Studies of Shear
Deformation of Mantle Materials - Towards Structural Geology of the
Mantle." Pure and Applied Geophysics 151(2-4): 589-603.
44.
Karlík, M., P. Homola, et al. (2004). "Accumulative
roll-bonding: first experience with a twin-roll cast AA8006 alloy."
Journal of Alloys and Compounds 378(1-2): 322-325.
An ultra-fine grained (UFG) material was prepared from a twin-roll cast
(TRC) Al–Fe–Mn–Si (AA8006) sheet using accumulative
roll-bonding (ARB) process. After initial failures to achieve good sheet
bonding, five cycles of ARB at 200 °C were successfully performed.
Scanning electron microscopy (Electron Backscatter Diffraction) and
transmission electron microscopy (TEM) were used for the characterization of
subgrain and grain structures of ARB processed samples. The strength of ARB
sheets was evaluated by microhardness measurements. Very fine grain
structure (0.4 – 0.8 µm) with large disorientation was observed
after two cycles of ARB. In two samples, areas with extremely fine grains
0.1–0.3 µm in diameter were found. The hardness of the alloy
increased from 28 to 60 HV1 after the first two cycles, but during
subsequent ARB processing it rose only very slightly.
45.
Karlsen, M., H. Norum, et al. (2004). SEM-EBSD characterisation of abnormal
grain growth in friction stir welded 2024 T351 aluminium alloy. European
Microscopy Congress 2004, Antwerp, Belgium.
46.
Karlsen, M., O. Frigaard, et al. (2003). SEM-EBSD Characterization of the
Deformation Microstructure in Friction Stir Welded 2024 T351 Aluminum Alloy.
Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications
Ltd.
In the present investigation, deformation microstructures forming during
friction stir welding (FSW) of the aluminum aerospace alloy 2024 T351 have
been examined. Electropolished specimen were examined by means of fully
automated electron backscatter diffraction (EBSD) analysis in a JEOL 840
scanning electron microscope (SEM) equipped with Nordif EBSD-hardware and
Channel 4.2 EBSD-software. The EBSD technique has proved to be a useful tool
for characterization of the deformation microstructures formed during
friction stir welding. Significant local variations in the deformation
microstructure are observed in the weld nugget region of the 2024 T351 alloy
in the as-welded condition. The grain structure shows characteristics
typical of different stages of dynamic recrystallization. In some regions a
fully recrystallized microstructure is observed, consisting of very fine 1-2
µm equiaxed grains mainly separated by high angle grain boundaries.
Other regions contain grains that are partially recrystallized with a
relatively large fraction of subgrains being observed. After high
temperature annealing at 500° C for 60 minutes it is evident that
abnormal grain growth has occurred in the weld nugget. This microstructure
contains a mixture of grains ranging from 4 µm up to about 170
µm.
47.
Karlsen, M., S. Tangen, et al. (2001). Characterisation of the Deformation
Microstructure in Friction Stir Welded 7075 T6 Aluminium Alloy using the
SEM-EBSD Technique. Third International Symposium on Friction Stir Welding,
Kobe, Japan, TWI Ltd.
In the present investigation the deformation microstructures forming during
friction stir welding (FSW) of 7075 T6 aluminium alloy have been examined.
This has been done by means of the electron backscattered diffraction (EBSD)
technique in a scanning electron microscope (SEM). In the as-welded
condition a dynamically recrystallised microstructure is revealed in the
weld region consisting of very fine 1-2 mu m equiaxed grains mainly
separated by high angle grain boundaries. The resulting pole figures show
evidence of sharp textures in the microstructure. However, different texture
components are observed in different regions of the weld nugget. After high
temperature annealing at 500 deg C for 60 minutes this microstructure
becomes unstable and is replaced by coarse irregular grains with different
texture components. The observed phenomenon bears a close resemblance to
secondary recrystallisation (or abnormal grain growth), which is
characterised by the rapid growth of a few grains in a recrystallisation
microstructure that already is stabilised by second phase particles (here
dispersoids) in the parent material.
48.
Karthikeyan, T., A. Dasgupta, et al. (2005). "Corrigendum to
"Study of texture in a TiTaNb alloy using electron back scattered
diffraction technique" Mater. Sci. Eng. A 393 (1-2) (2005)
294-302." Materials Science and Engineering A 405(1-2):
350-351.
The authors regret errors which appeared in Appendix A of the above article.
The complete text of Appendix A can be found below.
49.
Karthikeyan, T., A. Dasgupta, et al. (2005). "Study of texture in a
TiTaNb alloy using electron back scattered diffraction technique."
Materials Science and Engineering A 393(1-2): 294-302.
The development of texture during the β → α transformation
of a deformed and β-annealed alloy of Ti-5Ta-1.8Nb has been studied
using electron back scattered diffraction (EBSD) technique. The
microstructures that develop during the above transformation have been
characterized and correlated to their mechanism of formation. The X-ray
diffraction studies of the wire-drawn alloy suggested a development of
characteristic (1 0.0) type of deformation texture. Diffusion controlled
slow transformation of the alloy from above the β-transus resulted in a
completely different type of texture. The microstructure of this
transformation product consisted of colonies of alternate lamella of
coarse-α and fine-β together with α along the prior-β
grain boundary. EBSD results show that the crystallographic orientation of
α lamellae within a colony remains same and changes across the
colonies. The observation of a high full width at half maximum (FWHM) due to
scatter of the α poles suggests a deviation from an exact Burgers
relation. Comparison of experimentally measured misorientation angle between
different α-colonies with calculated values based on Burgers relation
enabled the identification of orientation of the parent-β grain. Thus a
method to characterise the diffusion controlled β → α +
β transformation in the Ti-5Ta-1.8Nb alloy has been developed combining
microscopy with EBSD studies. Copyright 2004 Elsevier B.V. All rights
reserved
50.
Kaschner, G. C., J. F. Bingert, et al. (2001). "Mechanical Response of
Zirconium—II. Experimental and Finite Element Analysis of Bent
Beams." Acta Materialia 49: 3097-3108.
In a companion paper [Acta mater. 2001, 49(15), 3085–3096] we develop
a polycrystal constitutive law that incorporates the deformation mechanisms
operating in high purity zirconium (Zr) at liquid nitrogen (LN) and room
temperature (RT). In this paper we present results of 4-point bending tests
performed on beams of highly textured zirconium. These tests have been
performed at LN and RT, in two orthogonal bending planes, and up to a strain
of approximately 20% in the outermost fibers of the beams. A novel
experimental technique, dot-matrix deposition and mapping (DMDM), has been
developed and employed to analyze the distribution of local plastic strain
and macroscopic deformation in the deformed beams. Automated electron
backscatter diffraction (EBSD) pattern analysis has been used to evaluate
the textures just below the outermost tensile and compressive surfaces and
at the neutral plane. Experimental results compare very well with the
predictions of finite element (FE) simulations obtained using the
constitutive law developed in Part I. Specifically, we compare local
deformation, macroscopic deformation and local texture in the beam. We show
that the contribution of twinning to deformation results in different
qualitative responses in the compressive and tensile fibers of the bent
beam. Our results indicate the necessity of using a constitutive description
that accounts for the anisotropy of the aggregate and for its evolution with
deformation.
51.
Kashihara, K. and J. A. Wert (2006). "The effect of a grain boundary on
deformation in an aluminum bicrystal with a common tensile axis of
100." Materials Transactions 47(1): 233-238.
The effect of a grain boundary on deformation has been examined using an
aluminum bicrystal specimen composed of crystals having a common tensile
axis of 100 by the measurement of orientation change with the electron
backscatter diffraction technique. After deformation to a strain of 20%, the
crystal rotation axis (CRA) map, which provides the orientation distribution
of crystal rotation axes relative to the initial crystal orientations,
reveals areas affected by the grain boundary. The thickness of the affected
zone was 100 µm in one crystal and 150 µm in the other. In both
crystals, the crystal rotation axis relative to the initial crystal
orientation differed between the affected zone and the crystal interior. In
the crystal interior, two slip systems showed a higher activity than the
other slip systems, whereas in the affected zone, three or four slip systems
were more active than the other slip systems. The CRA map showed that the
width and shape of the affected zones across the grain boundary were not
symmetrical with respect to the grain boundary.
52.
Kashihara, K., T. Okada, et al. (2004). SEM/EBSP and TEM Study of
Tensile-deformed Structure in Aluminum Bicrystal. Proceedings of the 8th
Asia-Pacific Conference on Electron Microscopy (8APEM). N. Tanaka, Y.
Takano, H. Moriet al. Ishikawa, Japan, 8APEM Publication Committee:
442-443.
SEM/EBSP (Electron Back-scatter Diffraction Pattern) and TEM analyses of an
aluminum bicrystal were performed to clarify the characteristic of
deformation structure (such as dislocations, slip bands and local
orientations) near a grain boundary. The OIM (Orientation Image Map) image
obtained from EBSPs was studied and compared with the slip band pattern
observed in SEM and the dislocation microstructure observed in TEM.
53.
Kashyap, B. P., A. Arieli, et al. (1985). "Microstructural Aspects of
Superplasticity." Journal of Materials Science 20(8):
2661-2686.
54.
Kashyap, B. P., W. Fan, et al. (2001). "Overview - Microtextural
Evolution During Superplastic Deformation of AA-Li-Alloy." Materials
Science and Technology 17(3): 237-248.
55.
Kaspar, R., D. Ponge, et al. (2004). "Grain boundary characterization
and grain size measurement in an ultrafine-grained steel." Zeitschrift
fur Metallkunde 95(6): 513-517.
Ultrafine ferrite grains in a plain C-Mn steel (0.3 mass% C) were produced
by large-strain warm compression and subsequent annealing treatment in a
temperature range between 773 K and 1003 K. The samples were investigated by
means of high-resolution electron back-scatter diffraction. The resulting
microstructures showed very fine ferrite grains and homogeneously
distributed cementite particles. The majority of the grain boundaries (55-70
%) were classified as high-angle ones (≥ 15° misorientation). When
considering only these high-angle grain boundaries, the average grain size
changed from 0.9 µm at a deformation temperature of 773 K to 2.2
µm at a deformation temperature of 1003 K. For the same range the
average subgrain sizes increased from 0.6 urn to 1.5 µm. The basic
result of this study is that the grain size characterization of
polycrystalline microstructures with ultrafine grains requires the use of
the high-resolution electron back-scatter diffraction method in conjunction
with a careful analysis of the grain boundary character.
56.
Kassner, M. E., M. Z. Wang, et al. (2002). "Large-Strain Softening of
Aluminum in Shear at Elevated Temperature." Metallurgical and Materials
Transactions A 33A(No. 10): 3145-3153.
Pure aluminum deformed in pure shear at elevated temperature reaches a broad
"peak" stress and then undergoes about a 17 pct. decrease in flow
stress with deformation with, roughly, 1 to 2 equivalent uniaxial strain.
Beyond this strain, the flow stress is approximately constant. The sources
for this softening are unclear. The suggested basis includes texture
softening, microstructural softening, enhanced dynamic recovery, and
discontinuous dynamic recrystallization. Experiments were performed in which
specimens were deformed in torsion to various strains within the softening
regime followed by compression tests at ambient and elevated temperature.
Analysis of the compressive yield strengths indicate that the softening is
most likely substantially explained by a decrease in the average Taylor
factor.
57.
Katrakova, D. and F. Mucklich (2000). "Investigation of the Corrosion
Steels in Marine Environment Using Orientation Imaging Microscopy."
Practical Metallography 37(12): 643-657.
Steels find a wide application for constructions in marine environment, such
as ships, platforms offshore and pipelines. Because of the sea water being a
highly aggressive medium, corrosion of these materials plays an important
role with respect to security and economy. The corrosion behavior is quite
different in the different crystal directions in the case of a single
crystal. In polycrystalline materials the chemical resistivity is dependent
not only on the chemical composition, but also on the orientation of the
grains and so on the texture of the sheet. The kind of grain boundaries is
another microstructural aspect of great importance here. In this paper
Orientation Imaging Microscopy (OIMTM) and White Light
Interfermotry (WLI) are used to investigate the correlation between
corrosion behavior and microstructure of low carbon steels for marine
application.
58.
Katrakova, D. and F. Mucklich (2001). "Specimen Preparation and
Electron Backscatter Diffraction - Part I: Metals." Practical
Metallography 38(10): 547-565.
This paper deals with specimen preparation for Electron Backscatter
Diffraction (EBSD). Due to the very low information depth of EBSD, the
standard metallographic preparation is typically not sufficient. It affords
an adjustment to better achieve a very flat and fully distortion free sample
surface. Compared to metals, the preparation of metallics is a bit more
delicate. Therefore it will be published separately. This article
concentrates on metals and includes general guidelines that would be helpful
to develop own recipes as well as their implementation in various successful
preparation routes for different metals and intermetallics, Which one is the
most appropriate will depend on the real chemical composition and on the
processing history of the material. The results are illustrated by a
representatice pattern and the corresponding pattern quality index (PQI)
that is suggeested as a relative measure for the preparation
quality.
59.
Katrakova, D. and F. Mucklich (2002). "Specimen preparation for
electron backscatter diffraction (EBSD). II. Ceramics." Practical
Metallography 39(12): 644-662.
For part I see ibid., vol. 38, p. 547 (2001). The second part of the paper
exclusively deals with specimen preparation of ceramics for EBSD. In
comparison with metals ceramics show particular difficulties, that set even
higher standards for the prepared sample surface. Concerning the processes
of grinding and polishing only those details are mentioned, that differ from
the principal methods worked out in part I. The possibilities to guarantee
electric conductivity on the sample surface are discussed in detail. For
five different types of ceramics successful preparation methods are
summarised in tables. The results are illustrated by a representative EBS
pattern and the corresponding pattern quality index (PQI). Some examples of
EBSD-application to different ceramic materials are also shown.
60.
Katrakova, D., C. Maas, et al. (1998). "Experiences on Contrasting
Microstructure Using Orientation Imaging Microscopy
(OIMTM)." Practical Metallography 3735(1):
4-20.
Orientation Imaging Microscopy (OIMTM) is one of the common terms
for the analysis of three-dimensional intensity distribution of
backscattered electrons in the Scanning Electron Microscope (SEM). This
three-dimensional density distribution (Kikuchi-Pattern) is determined by
the crystal lattice and its orientation in the irradiated region of the
sample. During the scannning of the sample by the electron beam, every step
of scan gives information about the crystal lattice and its orientation.
Analogous to Polarization Light Microscopy, a contrast within the polished
sample surface can be obtained as all adjacent scanning points of uniform
orientation belong to the same grain. Local changes of orientation suggest
the identification of a grain boundary. But the method requires a plane
polished surface of the sample with an extremely low residual lattice
deformation depth, as the depth of information submitted by backscattered
electrons is only about 0.02µ. In this paper examples are presented of
revealing microstructures by orientation contrast of soft and hard metallic
materials, as well as ceramic materials.
61.
Katrakova, D., F. Mücklich, et al. (2001). Specimen Preparation and
Electron Backscatter Diffraction. Proceedings of EuroMet 2002,
Saarbrücken, Progress in Metallography. F. Mücklich. Frankfurt,
Wekstoff-Informationsgesellschaft: 355-358.
Electron Backscatter Diffraction (EBSD) is meanwhile well established in
materials science. The method allows imaging of the true microstructure of
crystalline materials, since it is based on local lattice diffraction in a
very thin surface layer. The contrast is given through the orientation
differences of neighboring grains. Residual surface deformation leads to
blurring and poor contrast of the respective electron backscatter patterns
(EBSP). On the one hand, this suggests the use of the pattern quality as a
measure for the preparation quality. On the other hand, it requires
modification and adjustment of the standard preparation methods for the EBSD
application. In this study a set of materials that differ in their
preparation behavior and in their EBSD information depth are prepared in a
manner thet EBSP's of good quality are achieved. Some guidelines are
summarized.
62.
Kawaguchi, Y., J. Ohta, et al. (2005). "Room-temperature epitaxial
growth of GaN on lattice-matched ZrB2 substrates by pulsed-laser
deposition." Applied Physics Letters 87(22): 221907-1-3.
We have grown GaN films on ZrB2 substrates at room temperature
(RT) by using a pulsed-laser deposition technique. Reflection high-energy
electron diffraction observations have revealed that GaN growth can occur in
a layer-by-layer mode, even at RT, and that the surfaces of the films are
atomically flat. We found that intermixing reactions at the
GaN/ZrB2 heterointerfaces, which have been the most serious
problem for this structure until now, are well suppressed in the case of RT
growth. Electron backscattered diffraction measurements have revealed that
the tilt angle and the twist angle of the RT GaN are 0.23° and
0.24°, respectively, even for film thicknesses as low as 20 nm. The fact
that RT GaN exhibits quite high crystallinity from the early stages of film
growth can be attributed to the small lattice mismatch of this
system.
63.
Kazutaka, S., S. Ichinori, 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.
64.
Kell, J., J. R. Tyrer, et al. (2005). "Microstructural characterization
of autogenous laser welds on 316L stainless steel using EBSD and EDS."
Journal of Microscopy 217(2): 167-173.
This research is concerned with autogenous welding of 316L stainless steel
and the microstructure generated by such a process. Autogenous welding does
not require a filler material and in this case relies on an initial shallow
melt phase to maintain a conduction limited weld. Essentially, a high power
laser beam traverses the substrate, with the beam shaped by conventional
optics, which produces a Gaussian irradiance distribution; or with a
diffractive optical element, used to produce a uniform irradiance
distribution. Initial results have shown that due to the nature of the
heating cycle, complex microstructures are developed. These fine,
complicated microstructures cannot be satisfactorily resolved and quantified
using standard optical microscopy techniques. Electron backscatter
diffraction (EBSD) and energy dispersive spectroscopy (EDS) have been
carried out on a number of different microstructures prepared using a range
of welding parameters. It is demonstrated that the simultaneous
determination of the chemistry and crystallography is a very useful tool for
rapid identification of the different phases formed on solidification as a
consequence of varying welding procedures.
65.
Kell, J., J. Tyrer, et al. (2004). Computer generated holographic optics
used in laser powder fusion. 23rd International Congress, ICALEO 2004, San
Francisco, California, USA.
Autogenous (bead on plate) laser welding (1 kW CO2 laser) was
carried out on 316L stainless steel using both a Gaussian beam and a beam
shaped by computer generated holographic diffractive optical elements (DOE),
and the solidification microstructures were examined. The materials used
were 316L stainless steel sheet (1 mm thickness), with 316L stainless steel
powder for cladding operations. Various results are shown including a
cladding deposit produced at 600 W and 150 mm/min with pre-placed powder
depth of 0.5 mm, and DOE welds produced using power levels of 600-900 W and
traversing velocities of 50 to 90 mm/min. Microstructures were characterised
by optical microscopy, SEM, electron backscatter diffraction and energy
dispersive X-ray analysis.
66.
Keller, R. R., A. Roshko, et al. (2004). "EBSD Measurement of Strains
in GaAs due to Oxidation of Buried AlGaAs Layers." Microelectronic
Engineering 75(1): 96-102.
We have characterized elastric strain fields associated with the wet-thermal
oxidation of buried AlxGa1-x/As (x ~ 0.98) layers of
thickness 80 nm, situated between layers of thickness 200 nm, on a GaAs
substrate. The compressive strains accompanying oxidation can exceed 6% and
may lead to interlayer delamination or fracture. Automated electron
backscatter diffraction measurements were performed about individual oxide
growth fronts on longitudinally cross-sectioned samples. We found that the
elastic strain fields can be detected and mapped with a spatial resolution
of better than 30 nm, using pattern sharpness quantification. Measured
strain fields are elongated along the interfaces and extend approximately 1
µm around the growth front. We present efforts to quantify the spatial
extent of these strain fields, as well as finite element simulations of the
mechanics of oxide formation in this structure.
67.
Keller, R. R., J. A. Nucci, et al. (1997). "Local Textures and Grain
Boundaries in Voided Copper Interconnects." Journal of Electronic
Materials 26(9): 996-1001.
68.
Keller, R. R., R. H. Geiss, et al. (2005). Electric current induced
thermomechanical fatigue testing of interconnects. Characterization and
Metrology for ULSI Technology 2005, Richardson, Texas, USA.
We demonstrate the use of electrical methods for evaluating the
thermomechanical fatigue properties of patterned aluminum and copper
interconnects on silicon-based substrates. Through a careful selection of
alternating current frequency and current density, we used controlled Joule
heating to simulate in an accelerated manner the type of low frequency
thermal stress cycles that an interconnect structure may undergo. Sources of
such stressing may include power cycling, energy-saving modes, or
application-specific fluctuations, as opposed to stressing at chip operating
frequencies. The thermal stresses are caused by differences in thermal
expansion properties between the metal and constraining substrate or
passivation. Test conditions included a frequency of 100 Hz and current
density of 11-16 MAcm2, which led to a cyclic temperature
amplitude of approximately 100 K, and corresponding cyclic stress amplitude
in excess of 100 MPa for Al-1Si and Cu lines on oxidized silicon. The
failure mechanism differs from that observed in direct current
electromigration studies, and involves formation of localized plasticity,
which causes topography changes on the less-constrained surfaces of the
interconnect. Open circuit eventually took place by melting at a region of
severely reduced cross-sectional area. In these studies, both Al-1Si and Cu
responded to power cycling by deforming in a manner that was highly
dependent upon variations in grain size and orientation. Isolated patches of
damage appeared early within the confines of individual grains or clusters
of grains, as determined by automated electron backscatter diffraction. With
increased cycling or with increased current density, the extent of damage
became more severe and widespread. We discuss the utility of electrical
methods for accelerated testing of mechanical reliability.
69.
Keller, R. R., R. H. Geiss, et al. (2005). Microstructure Evolution during
Electric Current Induced Thermomechanical Fatigue of Interconnects.
Materials, Technology and Reliability of Advanced Interconnects-2005.
Symposium, San Francisco, California, USA, Materials Research
Society.
We demonstrate the evolution of microstructure and deformation associated
with the use of electrical methods for evaluating mechanical reliability of
patterned interconnects on rigid substrates. Thermomechanical fatigue in
aluminum and copper interconnects was induced by means of low frequency (100
Hz), high density (> 10 MA/cm2) alternating currents, which
caused cyclic Joule heating and associated thermal expansion strains between
the metal lines and oxidized silicon substrate. The failure mechanism
involved formation of localized plasticity, which caused topography changes
on the free surfaces of the metal, leading to open circuit eventually taking
place by melting at a region of severely reduced cross-sectional area. Both
aluminum and copper responded to power cycling by deforming in a manner
highly dependent upon variations in grain size and orientation. Isolated
patches of damage appeared early within individual grains or clusters of
grains, as determined by a quasi in situ scanning electron microscopy and
automated electron backscatter diffraction measurement. With increased
cycling, the extent of damage became more severe and widespread. We document
some examples of the types of damage that mechanically confined
interconnects exhibited when subjected to thousands of thermal cycles,
including growth and re-orientation of grains in a systematic manner. We
observed in the case of Al-1Si certain grains increasing by nearly an order
of magnitude in size, and reorienting by greater than 30 deg. The
suitability of electrical methods for accelerated testing of mechanical
reliability is also discussed.
70.
Kelly, G. L., H. Beladi, et al. (2002). "Ultrafine grained ferrite
formed by interrupted hot torsion deformation of plain carbon steel."
ISIJ International 42(12): 1585-1590.
A plain carbon steel was deformed using a hot torsion deformation simulator.
A schedule known to produce strain-induced ferrite was used with the strain
interrupted for increasing intervals of time to determine the effect of an
isothermal hold on the final microstructure. Microscopy and electron
back-scattered diffraction (EBSD) were used to analyse the changes that
occurred in the partially transformed microstructure during the hold and the
subsequent applied strain. The strain-induced ferrite coarsened during the
hold and this coarsened ferrite was refined during the second deformation.
These results were compared to those obtained for a different plain carbon
steel deformed in single pass rolling close to the Ar3
temperature. Material: AISI 1010.
71.
Kenik, E. A. (1996). Spatial resolution of electron backscatter diffraction
in a FEG-SEM. Mocroscopy and Microanalysis 1996. J. M. C. G. W. Bailey, R.
V. W. Dimlich, J. R. Michael, N. J. Zaluzec. San Francisco, San Francisco
Press, Inc.: 348-9.
72.
Kenik, E. A., C.-S. Man, et al. (2004). On the geometric autocorrelation
function of polycrystalline materials. International Conference on
Mathematics and its Application.
Herein we derive an expression for direct determination of the geometric
autocorrelation function W of a polycrystalline material from images of its
grain boundary network (e.g., those delivered by orientation imaging
microscopy). We also obtain an identity that relates the mean linear
intercept function to a directional derivative of the geometric
autocorrelation function. These formulae were applied to examine whether a
widely-used formula for W, particularly in theoretical studies of
attenuation of elastic waves in polycrystalline media, would be valid for
the grain boundary structure of a commercial aluminum alloy. The conclusion
was negative.
73.
Keshavarz, Z. and M. R. Barnett (2005). In-situ investigation of twinning
behaviour in Mg-3Al-1Z. 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.
Magnesium alloys are attractive for automotive and aerospace industries, due
to their low density. One problem with these alloys is their limited
formability at room temperature. Twinning plays a dominant role in
deformation behaviour and it can be expected that an increased understanding
of twinning will help improve formability. In the present work, the
behaviour of different twinning systems in as-cast Mg-3Al-1Zn is
investigated using in-situ tensile tests in a scanning electron microscope.
Electron backscatter diffraction and back scatter electron imaging were
carried out during the tests. The results show both "tension" and
"compression" twinning are active at room temperature and that
twinning and untwinning occur both during loading and unloading.
74.
Kestens, L., K. Verbeken, et al. (2005). The Use of Rodrigues-Frank Space
for Representing Discrete Misorientation Distributions. Textures of
Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
It is often assumed that the texture formation during solid state
transformations in low carbon steels critically depends on the local
crystallographic misorientation at the interface between transformed and not
yet transformed material volume. In some cases, a theoretical
crystallographic orientation relation can be presumed as a necessary
prerequisite for the transformation to occur. Classical examples of such
misorientation conditions in steel metallurgy are the orientation relations
between parent and product grains of the allotropic phase transformation
from austenite to ferrite (or martensite) or the hypothetical
<110>26.5º misorientation between growing nuclei and disappearing
grains in a recrystallization process. One way to verify the validity of
such misorientation conditions is to carry out an experiment in which the
transformation is partially completed and then observe locally, at the
transformation interface, whether or not the presumed crystallographic
condition is complied with. Such an experiment will produce a large set of
misorientation data. As each observed misorientation Δg is represented
by a single point in the Rodrigues-Frank (RF) space, a distribution of
discrete misorientation points is obtained. This distribution is compared
with the reference misorientation Δgr, corresponding to a
specific physical condition, by determining the number fraction dn of
misorientations that are confined within a narrow misorientation volume
element dω around the given reference misorientation
Δgr. In order to evaluate whether or not the proposed
misorientation condition is obeyed, the number fraction dn of the
experimentally measured distribution must be compared with the number
fractions dr obtained for a random misorientation distribution. The ratio
dn/dr can be interpreted as the number intensity fi of the given reference
misorientation Δgr. This method was applied on the observed
local misorientations between the recrystallizing grains growing into the
single crystal matrix of a Fe-2.8%Si alloy. It was found that the number
intensity of the <110>26.5º misorientation increased with a
factor 10 when the misorientation distribution was evaluated before and
after the growth stage. In another example the method was applied to the
misorientations measured at the local interface between parent austenite and
product martensite grains of a partially transformed Fe-28%Ni alloy. It
could be established that the Nishiyama-Wasserman relations
({111}γ//{110}α <112>γ//<110>α) prevail over
the Kurdjumov-Sachs relations ({111}γ//{110}α and
<110>γ//<111>α) although a considerable scatter was
observed around either of the theoretical correspondences. A full parametric
misorientation description was also applied to evaluate the relative grain
boundary energies associated with a set of crystallographic misorientations
observed near triple junctions in Fe-2%Si. In this instance it was found
that the boundaries carrying a misorientation of the type <110>ω
carry a lower interfacial energy than the <100> or <111> type
boundaries.
75.
Kestens, L., R. Decocker, et al. (2002). Orientation Selection during Phase
Transformation in Low Carbon Steels. ICOTOM 13, Seoul, Korea, Trans Tech
Publications Inc.
An elastic finite element code is applied to study the crystallographic
variant selection which is associated with the allotropic phase
transformation during thermo-mechanical processing of low-carbon steel
sheets. A transforming ferrite nucleus is embedded as a single element in an
austenite parent matrix of cubic shape and with fixed sides. The Bain strain
of the transforming nucleus is regarded as an eigenstrain which provokes an
elastic response in the surrounding austenite grains. For each of the three
possible Bain variants the elastic strain energy is calculated after the
stress equilibrium has been obtained and the one variant is selected which
minimizes the energy of the assembly. With an appropriate sampling procedure
a statistical representative local environment of the transforming nucleus
is constructed from a given arbitrary parent texture consisting of a number
of discrete orientations.
76.
Khalfallah, O. and L. Priester (1980). "Investigation of Extrinsic
Grain-Boundary Dislocations in Iron, Iron-Chromium and
Iron-Nickel-Alloys." Scripta Metallurgica 14(8):
839-843.
77.
Khalfallah, O. and L. Priester (1981). "Interaction Between Extrinsic
Grain-Boundary Dislocations and Carbon Impurity in Iron and BCC
Iron-Alloys." Revue de Physique Appliquee 16(4):
153-163.
78.
Khalfallah, O. and L. Priester (1988). "Influence of the
Crystallography on the Incorporation of Lattice Dislocations in
Grain-Boundaries." Journal de Physique I 49(NC-5):
435-440.
79.
Khalfallah, O., C. Bouchet, et al. (1980). "Influence of Carbon on the
Presence of Extrinsic Defects in the Grain-Boundaries of Iron and
Fe-9-Percent CR Alloy." Memoires et Etudes Scientifiques de la Revue de
Matallurgie 77(11): 985-991.
80.
Khan, A., D. T. Carpenter, et al. (2001). "Electron Backscatter
Diffraction Analysis of Pb(Mg1/3Nb2/3)O-3-35Mo-Percent PbTiO3 Single-
Crystals Grown by Seeded Polycrystal Conversion." Journal of Materials
Research 16(3): 694-700.
81.
Khangar, A. A., E. A. Kenik, et al. (2005). "Microstructure and
microtexture in laser-dressed alumina grinding wheel material."
Ceramics International 31(4): 621-629.
Alumina grinding wheels when laser dressed with a high-power laser induce
change in the morphology of the wheel surface. The altered grain structure
on the surface of the wheel gives laser dressing advantage over conventional
mechanical methods. Morphological modification during laser dressing is
strongly influenced by the microstructure formed during the rapid
solidification process. Microstructure depends mainly on the cooling rates
amongst many other factors related to the laser processing conditions. Using
a two-color based pyrometer temperature measurement setup the cooling rates
were estimated during the laser dressing process. Orientation imaging
microscopy (OIM) was used to determine the grain orientations in the
resolidified layer on the dressed surface. Cooling rates and the OIM
combined, indicate a preferred orientation of grains along the (110) planes.
This preferred orientation can be a reason for the formation of grains with
multi-faceted surfaces having cutting edges and vertices, for grinding
operation. OIM and cooling results also show existence of a competitive
growth mechanism for the grains in the dressed layer.
82.
Khlopkov, K., O. Gutfleisch, et al. (2004). "Local texture in Nd-Fe-B
sintered magnets with maximised energy density." Journal of Alloys and
Compounds 365: 259-265.
Sintered Nd-Fe-B magnets, one of which showed a maximised energy density as
high as (BH)max=451 kJ/m3 (56.7 MGOe) at room
temperature, have been produced by optimisation of alloy composition,
minimisation of impurities, improved alignment of the powder particles and a
controlled sintering process. For the first time, large scale microtexture
analysis using electron backscatter diffraction (EBSD) has been carried out
on sintered Nd-Fe-B magnets. Large orientation maps in both directions,
parallel and perpendicular to the texture axis, were acquired in a thermal
field emission gun scanning electron microscope (FEGSEM). Domain patterns of
the same areas have been obtained using magneto-optical Kerr-microscopy.
Thereby, a quantitative description of local texture could be correlated
effectively with domain patterns of individual grains and with backscattered
electron images. Distinction between individual grains in the Kerr-images
was more difficult due to the excellent alignment of the grains in the
magnet with the maximised energy density. Pole figures were used to evaluate
EBSD patterns.
83.
Khodabandeh, A. R., M. Jahazi, et al. (2005). "Impact Toughness and
Tensile Properties Improvement through Microstructure Control in Hot Forged
Nb-V Microalloyed Steel." ISIJ International 45(2):
272-280.
The influence of thermomechanical processing parameters such as reheating
temperature, deformation temperature, deformation percent and cooling rate
on achieving high impact toughness properties was studied in a Nb-V
microalloyed steel to be used as forged parts in automotive applications. 15
mm long and 65 mm diameter billets were forged using a 20 MN mechanical
press. Tensile and Charpy impact tests specimens were machined out of the
central part of the forged billets. The microstructure of the specimens was
examined for each experimental condition using optical microscopy. Phase
identification and distribution was studied using X-ray diffraction and
orientation image microscopy techniques. The results indicate that,
increasing the reheating temperature above the dissolution temperature of
(Nb)(C, N) improved the impact energy values. By increasing the cooling rate
from 0.3 to 3DGC/s both tensile strength and impact toughness were improved.
High elongation percent was also observed on samples reheated at higher
temperature and/or cooled with the higher cooling rates. The obtained
mechanical properties were related to the characteristics of microstructural
components including acicular ferrite, retained austenite, pearlite and
ferrite. The interrelationship between thermomechanical processing
parameters, microstructure development, and final mechanical properties were
identified and optimized forging conditions to obtain high impact energy
(>30 J) microalloyed forge steels were determined.
84.
Khraisheh, M. K., B. M. Darras, et al. (2004). Correlation Between the
Microstructure and Forces Generated During Friction Stir Processing of
AA5052. The Fifth Pacific Rim International Conference on Advanced Materials
and Processing, Beijing, China, Trans Tech Publications Ltd.
The microstructure of friction stir processed AA5052 sheets is investigated
using Scanning Electron Microscopy (SEM) and Orientation Imaging Microscopy.
The correlation between the generated forces during processing and the
microstructure is evaluated. Observations indicate that the finest
microstructure are achieved when the plunging forces are at minimum.
85.
Kiaei, M., B. Bacroix, et al. (1995). "Development of Recrystallization
Textures in Deep-Drawing Steels, Measured by X-Ray Diffraction and
EBSD." Journal de Physique IV 5: C3-67-75.
86.
Kim, B.-K. and J. A. Szpunar (2001). "Orientation imaging microscopy
for the study on high temperatire oxidation." Scripta Materialia
44(11): 2605-10.
87.
Kim, B.-K. and J. A. Szpunar (2002). Anisotropic Microstructure of Iron
Oxides Formed during High Temperature Oxidation of Steel. ICOTOM 13, Seoul,
Korea, Trans Tech Publications Inc.
The microstructure, phase composition and texture of iron oxides formed
during slab preheating and hot rolling operation may affect the process of
descaling. A role these microstructural parameters play is not yet well
understood. In this paper structure, texture and phase composition of oxides
formed on pure iron, low-carbon steel, and Si-steel are systematically
investigated by X-ray diffraction texture measurement and electron back
scattered diffraction (EBSD). The experiments are designed to understand the
characteristics of oxide under the continuous heating applied in industrial
practice. It is demonstrated that the EBSD technique is an excellent tool to
visualize the oxide microstructure and microtexture. Iron oxides developed
during high temperature oxidation consist of hematite
(Fe2O3), magnetite (F3O4), and
wustite (FeO). The columnar structure of magnetite and wustite was observed
after high temperature oxidation. Detailed characteristics of oxide
structure are presented in this paper.
88.
Kim, B.-K., J. A. Szpunar, et al. (2002). Microstructure and Texture
Evolution during Superplastic Deformation of 7475 Al Alloy. ICOTOM 13,
Seoul, Korea, Trans Tech Publications Inc.
Various microstructural characteristics of superplasticity in a 7475
aluminum alloy are evaluated. The microstructure evolution in the process of
superplastic deformation (SPD) is characterized by X-ray texture
measurements and the EBSD technique. The specimens were pulled in tension at
the initial strain rate 5.6x10-4s-1 after the holding
time of 1800 seconds at 803 K. The major texture component in as-prepared
7475 aluminum alloys is a Cube {001}<100> texture. The intensity of
the Cube texture and other texture components is decreased and grain
orientations become more random after superplastic elongation. However, the
evolution of the Brass {011}<112> component and the increase in
percentage of the coincidence site lattice boundaries fraction shows that
the mechanism in the initial stage of SPD may be governed by
crystallographic slip. Details of the SPD process are discussed for
different strains at a given pulling speed and for different pulling speeds
at a given strain.
89.
Kim, B.-K., J. A. Szpunar, et al. (2002). Texture Evolution in Grain Growth
of Nanocrystalline Ni. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
The mechanism of transformation of nanocrystalline Ni into its
polycrystalline structure is not well understood. The transformation of
texture and microstructure is investigated in this paper by X-ray
diffraction measurements and also more directly by orientation imaging
microscopy (OIM). The microstructure after systematic annealing was recorded
using the OIM and it was found that the final annealing texture depended on
the initial texture. The factors controlling annealing texture in
nanocrystalline Ni are annealing temperature, time and heating rate. It is
clear, however, that this grain growth is accompanied by strengthening of
the <111>//ND texture. The competition in growth between the (111) and
(100) grains is followed during the annealing treatment up to 400°C. It
is also demonstrated that the microstructure obtained after annealing had a
higher fraction of special grain boundaries (sigma3 in the coincidence site
lattice). It is possible to use the formation of coherent twin boundaries to
explain the mechanism of texture evolution and growth of (111)-fibre
grains.
90.
Kim, B.-K., J. A. Szpunar, et al. (2002). Annealing Texture in Thermal
Stability of Ultrafine-Grained Ni. ICOTOM 13, Seoul, Korea, Trans Tech
Publications Inc.
In order to commercialize the ultrafine-grained material, it is important to
understand and improve their thermal stability. Ultrafine-grained materials
can be easily transformed into microcrystalline structure because of their
low thermo-stability. In this paper, the annealing behavior of
ultrafine-grained Ni fabricated by high pressure torsion (HPT), was
investigated by analysing grain growth and texture transformation. X-ray
diffraction and orientation imaging microscopy (OIM) were used to analyse
texture transformation, microstructure and grain boundary character
distribution (GBCD). These investigations demonstrated that grains with a
near <112>//ND texture grow abnormally in the initial stage of
annealing and the fraction of sigma 3 coincidence site lattice boundaries
increased during annealing at 300°C.
91.
Kim, C.-S. and G. S. Rohrer (2004). "Geometric and Crystallographic
Characterization of WC Surfaces and Grain Boundaries in WC-Co
Composites." Interface Science 12(1): 19-27.
Electron backscattered diffraction has been used to determine the
orientation of WC crystals in a WC-Co composite and atomic force microscopy
has been used to measure the shapes of planar sections of the same crystals.
A stereological analysis has been used to determine that {101-0} prism
facets and the {0001 } basal planes are the WC surfaces that are most
frequently in contact with Co. Further, the WC habit is an approximately
equiaxed trigonal prism bound by three prism facets and two basal facets. An
analysis of similar to 15,600 grain boundaries shows that certain interfaces
occur with a frequency that is much higher than would be expected in a
random distribution and that the grain boundary habit planes also have
{101-0} and {0001} orientations. Eleven percent of all the observed WC-WC
interfaces are 90° twist boundaries about 101-0. Two types of boundaries
with a 30° rotation about 0001, a twist and an asymmetric tilt, comprise
3% of the population.
92.
Kim, C.-S. M., Ted R; Rohrer, Gregory S. (2004). Modeling the relationship
between micro structural features and the strength of WC-Co composites. The
Eighth International Conference on the Science of Hard Materials (ICSHM8),
San Juan, Puerto Rico.
A two-dimensional finite element method (FEM) was used to predict the
stress-strain distributions and the fracture strengths of WC-Co composites
with carbide grain sizes from 1.4 to 5.3 mum and carbide volume fractions
from 0.7 to 0.9. Stress-strain distributions were calculated in plane
sections of microstructures mapped by orientation imaging microscopy. An
effective fracture energy was set so that the measured strength of each
material was reproduced by the simulation. This model was then used to
simulate the properties of hypothetical microstructures to investigate the
influence of independent variations in microstructural characteristics on
strength. The results indicate that composites with minimum contiguity,
containing highly angular, and equiaxed carbide grains with a narrow size
distribution should have the maximum strength. Of these parameters,
contiguity is the most influential.
93.
Kim, C.-S., Y. Hu, et al. (2005). "Five-parameter grain boundary
distribution in grain boundary engineered brass." Scripta Materialia
52(7): 633-637.
The superplasticity of commercially pure titanium alloy at high temperature
was studied and the dynamic recrystallization phenomenon of the alloy was
investigated by using electron back scattered diffraction. A two-step
deformation method was used to increase the ductility of the alloy from 188%
to 243%. Copyright 2004 Published by Elsevier Ltd. All rights
reserved.
94.
Kim, D.-I., J.-H. Lee, et al. (2002). EBSD Analysis of Grain Boundary
Characteristics of Abnormally Grain Grown Alumina. ICOTOM 13, Seoul, Korea,
Trans Tech Publications Inc.
Electron Back Scattered Diffraction (EBSD) analysis was carried out to
investigate boundary characteristics of Abnormal Grain Growth (AGG) Alumina.
To obtain whole orientation information from AGG Alumina, separately
measured EBSD mapping data was combined together to be satisfied with
condition of minimum misorientation, which is called Montage technique. The
orientation information from 0.5 x 3.5 mm and 0.35 x 1.00 mm sizes of AGG
alumina was obtained. Misorientation distribution in Normal Grain Growth
(NGG) Alumina was very close to the random misorientation boundary.
Misorientation distribution between AGG and NGG alumina showed random
boundary characteristics in 0.5 x 3.5 mm AGG alumina. Large part of captures
grain inside AGG grain has high angle boundary of 90°.
95.
Kim, D.-I., J.-M. Paik, et al. (2002). Microtexture Measurement of Copper
Damascene Line with EBSD. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
Microtexture of 0.18µm, 0.25µm, 0.70µm, and 2µm
widths Cu damascene line is measured by EBSD technique. The image drift
could be reduced by the shortening of measurement time, and could be
completely removed by selected area mapping technique. Using carbon and gold
dual layer coating method, image drift and pattern indexing fraction is
improved but the EBSD pattern quality is decreased. By increasing the
acceleration voltage from 15kV to 20kV, pattern quality loss could be
compensated without resolution loss. Strong {111} texture is obtained in
0.18 and 0.25µm line, and weal {111} texture is observed in 2µm
line. And every line was observed to have more than 60% CSL
boundaries.
96.
Kim, D.-I., K. H. Oh, et al. (2002). Statistical Analysis of the Development
of Recrystallization Texture in IF Steel. ICOTOM 13, Seoul, Korea, Trans
Tech Publications Inc.
Development of recrystallization texture an an IF Steel containing
0.002wt%C, 0.06wt%Ti is investigated by EBSD technique. Strong a-fiber
texture, maximum at {112}<110> is developed in cold rolled state, and
strong?-fiber texture, which has a maximum value at {111}<112>, is
developed after annealing in salt bath. A technique to set a criterion
distinguishing recrystallized grains from deformed grains is suggested.
Grains of high orientation consistency are regarded as recrystallized, and
grains of high orientation deviation are looked upon as deformed.
Recrystallized grains are classified by their size, and texture development
is analyzed according to the annealing time and grain size variation.
Texture of the recrystallized grains is relatively weak?-fiber and
significant fraction of {001}<110> texture at the early stage of
recrystallization, but strong?-fiber texture with {111}<112> peak is
developed at the final stage of recrystallization. In every stage, small
sized recrystallized grains have weak {001}<110> texture, and it
disappears in large size recrystallized grains.
97.
Kim, D.-I., K. H. Oh, et al. (2004). "Characterization of
crystallographic properties of SMC poly Si using electron backscattered
diffraction." Journal of Microscopy 215: 121-126.
Crystallographic properties of silicide mediated crystallization (SMC)
polycrystalline silicon (poly Si) and excimer laser annealing (ELA) poly Si
were studied by electron backscattered diffraction. Large-grain sized poly
Si with a large fraction of low-angle grain boundaries was acquired by SMC,
and smallgrain sized poly Si with high-angle grain boundaries especially
around 60 ° was acquired by ELA. The thin film transistor (TFT) device
characteristics were investigated in view of short-range crystallinity
(pattern quality) and long-range crystallinity (misorientation distribution)
of the specimens. Short-range crystallinity did not significantly affect the
TFT device characteristics, and long-range crystallinity considering the low
energy level of special boundaries could be better related to the TFT device
characteristics of poly Si.
98.
Kim, H. G., H. M. Lee, et al. (2005). "The influence of misorientation
deviation on the faceting of E3 grain boundaries in aluminium."
Zeitschrift fur Metallkunde 96(2): 216-219.
The faceting of two tilt grain boundaries (GBs) in 99.999 % wt. purity Al
bicrystals has been studied. The first GB is a coincidence twin E3
<110> GB (E is the inverse density of coincidence sites) and the
second GB has a misorientation close to the E3 <110> with a tilt
deviation of about 3 degrees. Orientation of grains along the GB has been
controlled with the electron back-scattering diffraction method. The
bicrystalline samples were coated with a layer of SnAl mixture and annealed
at 873 K. Contact angles at the junction of the grain boundary and two
solid/liquid interfaces were measured by optical microscopy. The ratio of
grain boundary energy and solid/liquid interface energy has been calculated.
Wulff-Herring plots and GB phase diagrams were constructed. The formation of
smooth edges with rounded rough GB portions was observed in the grain
boundary deviating from E3 <110>.
99.
Kim, J. K., J. H. Seo, et al. (2004). Grain Growth and Texture Development
in Nanostructured Invar Alloy. Second Joint International Conference on
Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France,
Trans Tech Publications Ltd.
In the present work, a nanocrystalline Invar alloy (Fe-36wt%Ni) foil was
fabricated by using a continuous electroforming method. This material
exhibited outstanding mechanical properties and a relatively low thermal
expansion coefficient as compared to conventional Invar alloys. The
as-deposited texture was of fibre-type characterized by strong < 100 >
//ND and weak < 111 > //ND components. Grain growth occurred during
annealing beyond 350DGC and resulted in such texture change that the <
111 > //ND fibre texture strongly developed with the minor < 100 >
//ND components. It was clarified using orientation imaging microscopy that
abnormal growth of the < 111 > //ND grains in the early stages of
grain growth plays an important role on the texture evolution. The mechanism
of the abnormal grain growth has been discussed in terms of the orientation
dependence of energy density.
100.
Kim, J.-D., K.-W. Lee, et al. (2004). Origin of grain boundaries in
liquid-phase-sintered WC-Co alloys. Powder Metallurgy World Congress &
Exhibition (PM2004), Vienna, Austria, European Powder Metallurgy
Assoc.
The origin of WC/WC grain boundaries in liquid-phase-sintered WC-Co alloys
has been investigated in a WC-Mo2C-Co model system using coarse
WC polygrain powder. The evolution of grain shape during liquid phase
sintering was able to be identified by observing a growth layer that
contained Mo. During liquid phase sintering most of the grain boundaries in
the powder were penetrated by a Co liquid but some of them were not. EBSD
analysis showed that some boundaries in the powder, in particular Sigma 2
twist boundaries and Sigma 97 special boundaries, remained intact during
liquid phase sintering. These experimental results confirm that the grain
boundaries of WC grains in liquid-phase-sintered WC-Co alloys are originated
from those present in the starting powder.
101.
Kim, J.-D., S.-J. L. Kang, et al. (2005). "Formation of Grain
Boundaries in Liquid-Phase-Sintered WC-Co Alloys." Journal of the
American Ceramic Society.
The origin of WC/WC grain boundaries in liquid-phase-sintered WC-Co alloys
was investigated in a WC-Mo2C-Co model system using coarse WC polygrain
powder. The evolution of grain shape during liquid phase sintering could be
identified by observing a growth layer that contained Mo. During liquid
phase sintering, most of the grain boundaries in the powder were penetrated
by a Co liquid but some of them were not. Electron backscattered diffraction
analysis confirmed that some boundaries in the powder, in particular, S2
twist boundaries and Σ97 special boundaries, remained intact during
liquid phase sintering. These experimental results confirm that the grain
boundaries of WC grains in liquid-phase-sintered WC-Co alloys originated
from those present in the starting powder.
102.
Kim, K.-H., H.-K. Kim, et al. (2006). "Deformation behavior of pure
aluminum specimen composed of a few grains during simple compression."
Journal of Materials Processing Technology 171(2): 205-213.
In this study, the grain-by-grain deformation of aluminum specimens with a
few grains during simple compression is investigated experimentally. This
experiment is conducted to verify the simulation technique based on the
crystal plasticity model with which grain-by-grain deformation behavior can
be anticipated. 99.99% polycrystalline aluminum cubes with dimensions of 3mm
x 3mm x 3mm is tested. By applying consecutive heat treatments, the grain
size of the aluminum specimens is grown to a size with a diameter of 1-3mm.
The specimens used in this study can be classified into two types: the
specimens predominated by a single grain (type1) and the specimens composed
of several grains (type2). The individual surface grain orientations of the
initial specimens are measured by electron backscattered diffraction (EBSD)
system, and then the specimens are compressed to 70% of the initial height.
The resultant deformations of the type1 specimens are then compared with the
calculations based on the crystal plasticity. For the type2 specimens,
finite element method (FEM) using the crystal plasticity material model is
adopted to predict the complicated grain-by-grain deformations. However, as
the inner grain distribution cannot be measured by EBSD in the present
investigation, the experimentally observed deformations of the type2
specimens are not directly compared with the corresponding FEM predictions.
Instead, the similarity between the experimental observations and the FEM
predictions is compared in a qualitative manner.
103.
Kim, M.-C., K.-M. Lim, et al. (2004). "Effects of Si addition on the
microstructure and magnetic properties of permalloys fabricated by melt drag
casting." JOM 56(11): 215.
Effects of Si addition on the microstructure and magnetic properties of
79Ni-Fe based permalloys, fabricated by melt drag casting, has been
investigated. The Permalloy strips of 50mm width obtaining various Si
contents were successfully prepared by melt drag casting, which was newly
applied to fabrication of the permalloy strips in this study. In order to
understand the relationship between magnetic properties and Si contents,
microstructure and texture were extensively analyzed by TEM and EBSD
Increasing Si contents improved permeability of the permalloys in low Si
content region below 2% due to the enlarged grain size. In high Si content
region more than 2%, the formation of Ni3Fe ordered phase was revealed
remarkably, which caused the drastic reduction of permeability. In addition,
the formation of Ni3Fe was promoted by higher temperature annealing at fixed
Si content. From these results, the ordering kinetics of Ni3Fe in Si added
permalloys will be discussed.
104.
Kim, M.-C., Y. J. Oh, et al. (2000). "Characterization of boundaries
and determination of effective grain size in Mn-Mo-Ni low alloy steel from
the view of misorientation." Scripta Materialia 43(No. 3):
205-11.
105.
Kim, M.-C., Y. J. Oh, et al. (2001). "Relationship Between
Crystallographic Orientation at the Boundaries and Brittle Crack-Propagation
in Mn-Mo-Ni Low-Alloy Steel." Metallurgical and Materials Transactions
A 32(8): 2139-2142.
106.
Kim, M.-S., J.-S. Lee, et al. (2005). "Control of the crystal
orientation in metal-induced lateral crystallization." Journal of the
Korean Physical Society 47: S404-7.
The effects of crystal filter on MILC poly-Si were investigated. When
amorphous Si was crystallized by a metal-induced lateral crystallization
(MILC) method, the poly-Si was contaminated with silicide. So, we formed
crystal filter in an amorphous Si (a-Si) layer and crystallized a-Si to
poly-Si. Then, we compared the MILC which passed the crystal filter
(CF-MILC) with the conventional MILC region which did not pass the crystal
filter region. We also observed a change of MILC growth rate. It turned out
that poly-Si which passed the crystal filter region had a greater
unioriented poly-Si region than unfiltered crystal (conventional MILC)
region. The narrower the width of crystal filter, the more effectively the
crystal orientation was unified. The growth rate of CF-MILC changed as well.
It was found that the MILC growth rate depended on the width of crystal
filter. The microstructure of CF-MILC was observed by means of electron
backscattering diffraction and scanning electron microscopy.
107.
Kim, M.-S., J.-S. Lee, et al. (2006). "The effects of crystal filtering
on growth of silicon grains in metal-induced lateral crystallization."
Electrochemical and Solid-State Letters 9(2): G56-58.
We have investigated the effect of crystal filtering on the microstructural
evolution of amorphous silicon (a-Si) during metal-induced lateral
crystallization (MILC). Polycrystalline silicon (poly-Si) with uniform
surface-crystallographic orientation was prepared by preferred filtration of
poly-Si through the narrow neck of the a-Si region, which is named as a
crystal filter (CF). It is found that the width of the CF is the dominant
factor for determining the preferred crystalline orientation. The
crystallization behavior formed by CF-MILC was confirmed by electron
backscattering diffraction, transmission electron microscopy, and scanning
electron microscopy.
108.
Kim, N. J., Y. M. Kim, et al. (2005). Microstructural characteristics of
acicular ferrite in linepipe steels. 15th International Offrshore and Polar
Engineering Conference, ISOPE-2005, Seoul, South Korea.
The present study is aimed at systematically investigating the
microstructural characteristics of acicular ferrite. The effect of
hot-deformation on the formation of acicular ferrite was investigated for
the steels with different alloy compositions. The formation mechanism and
morphological characteristics of acicular ferrite were analyzed by using
dilatometer and EBSD The results show that as amount of hot-deformation in
austenite non-recrystallization region increased, the volume fraction of
acicular ferrite increased, indicating that acicular ferrite form at the
nucleation sites within austenite grains such as dislocations. It has also
been shown that an acicular ferrite grain consists of several sub-units
misoriented by 1-2 microstr.
109.
Kim, S. and T. J. Marrow (1999). "Application of electron backscattered
diffraction to cleavage fracture in duplex stainless steel." Scripta
Materialia 40(No. 12): 1395-1400.
The mechanical properties and corrosion resistance of duplex stainless steel
(DSS) are generally superior to conventional austenite or ferrite grades.
DSSs can have yield strengths twice the austenite grades, while retaining
good ductility and toughness properties [1]. Commercial wrought duplex
stainless steels, either plates or rod, are processed by hot rolling
followed by a solution annealing treatment to optimize the austenite-
ferrite ratio and dissolve any pre-existing secondary phases [2]. Processing
may lead to a significant anisotropy in mechanical properties [3]. For
example, the tensile properties in cold-rolled sheet of duplex stainless
steel (22Cr5Ni) reveals anisotropy of strength, i.e. the transverse
direction tensile strength is 7.3% higher than tensile strength in the
rolling direction (RD). It was also shown in a study of the effect of crack
orientation on the impact properties of the same steel, that when the crack
was oriented parallel to the direction of elongation of the austenite phase,
the crack could grow along the more brittle ferrite phase for a longer
distance before encountering the more ductile austenite [4]. This decreased
impact toughness. These are examples of microstructure texture.
Crystallographic texture may also have an effect on properties that are
related to specific crystallographic planes; such as brittle cleavage and
stress corrosion cracking. This paper describes the application of electron
backscattered diffraction (EBSD) to study cleavage fracture and crystal
texture in age-hardened DSS.
110.
Kim, S. I., S. H. Choi, et al. (2005). "Influence of phosphorous and
boron on dynamic recrystallization and microstructures of hot-rolled
interstitial free steel." Materials Science and Engineering A
406(1-2): 125-133.
This paper examines the effects of phosphorous (P) and boron (B) of Nb-Ti
added interstitial free (IF) steel on dynamic recrystallization, mechanical
properties and microstructures. For this purpose, four Nb-Ti added IF steels
that contain different contents of P and B were selected. The dynamic
recrystallization behavior was investigated using hot compression testing.
Mechanical properties and microstructures of pilot hot-rolled IF steel sheet
were analyzed as well using uni-axial tensile test and electron
back-scattered diffraction (EBSD) following pilot hot rolling experiment. It
has been found that B strongly retarded dynamic recrystallization of the IF
steel in the temperature range of 900-1100 DGC. However, P did not delay
dynamic recrystallization at 1100 DGC. The effect of P on dynamic
recrystallization was less than that of B. EBSD analysis revealed that
absence of P and B induced fine ferrite grain size and many high angle grain
boundaries. The ferrite grain size of P and B free IF steel was 46.4%
smaller than that of IF steel having 0.1% of P and 0.001% of B.
111.
Kim, S. I., S.-H. Choi, et al. (2005). Influence of Boron on Mechanical
Properties and Microstructures of Hot-Rolled Interstitial Free Steel.
Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech
Publications.
This paper examines an effect of boron (B) on dynamic softening behavior,
mechanical properties and microstructures for Nb-Ti added high strength
interstitial free (IF) steel. For this purpose, IF steels containing 0ppm B,
5ppm B and 30ppm B were chosen. Continuous cooling compression test was
performed to investigate dynamic softening behavior. Mechanical properties
and microstructures of pilot hot-rolled IF steel sheet were analyzed by
uni-axial tensile test and electron back-scattered diffraction (EBSD).
It was found that no-dynamic recrystallization temperature (Tndrx) which can
be determined from the relationship between flow stress and temperature is a
constant of 955°C for all IF steels. However, an addition of B into IF
steels increases work hardening rate at the temperature below Tndrx. It was
also verified that B retards phase transformation of austenite into ferrite.
EBSD analysis revealed that absence of B induces fine ferrite grain size and
many high angle grain boundaries.
112.
Kim, S., B. S. Lee, et al. (2003). "Effects of grain size on fracture
toughness in transition temperature region of Mn-Mo-Ni low-alloy
steels." Materials Science and Engineering A 359(1-2):
198-209.
An investigation was conducted into the effect of grain size on fracture
toughness in the transition temperature region of Mn-Mo-Ni low-alloy steels
used for nuclear pressure vessels. Three kinds of steels with different
austenite grain sizes (AGS) were fabricated by varying the contents of Al
and N, and their microstructures and mechanical properties were examined.
Elastic-plastic cleavage fracture toughness, KJc, was determined
by three-point bend tests of precracked Charpy V-notch (PCVN) specimens
according to ASTM E1921 standard test method. When the AGS decreased, the
total number of carbides increased, while the size and the aspect ratio of
carbides decreased. Local fracture stresses, estimated from a theoretical
stress distribution in front of a crack tip, were found to be mainly
determined by the 92nd% size of carbides. Cross-sectional areas beneath
fracture surfaces were observed to understand microstructural features to
affect the cleavage crack propagation behavior. The results showed that
measured cleavage fracture units were smaller than AGSs, indicating that
packet boundaries as well as austenite grain boundaries played an important
role in the cleavage crack propagation. Based on the electron back-scatter
diffraction (EBSD) results, the cleavage fracture units could also be
matched with the effective grain sizes determined by the misorientation
tolerance angle of 25t of the. Copyright 2003 Elsevier B.V. All rights
reserved
113.
Kim, S.-H. and D. N. Lee (2002). "Annealing Behavior of Alumina
Dispersion-Strengthened Copper Strips Rolled under Different
Conditions." Metallurgical and Materials Transactions A
33(June): 1605-1616.
A study has been made of annealing behavior of a boron-added alumina
dispersion-strengthened copper (ADSC) strip, Glidcop Al-25, and specimens
fabricated by rolling of the strip by 25 to 28 pct under various conditions.
All the specimens, including the starting strip, had similar microstructures
consisting of microbands alligned parallel to the rolling direction. The
textures of the specimens were characterized by ß fiber, which runs
from the copper orientation {112}<111> over the S orientation
{123}<634> to the brass orientation {110}<112> in the Euler
orientation space, with the intensities in the S and the brass components
being higher than the copper component and with the S components having
higher intensities than the brass component in the surface layers. When
annealed at 1123 K for 1 hour, the center region of the starting strip and
cold-rolled specimens underwent recrystallization, with recrystallization
texture being approximated by {112}<312>, whereas the specimens rolled
at 813 K did not undergo recrystallization through the thickness. These
results have been discussed based on detailed micrsostructures and
microtextures.
114.
Kim, S.-H. and D. N. Lee (2002). Rolling and Annealing Textures of
Dispersion Strengthened Copper Strips. ICOTOM 13, Seoul, Korea, Trans Tech
Publications Inc.
The evolutions of the rolling and annealing textures of boron added alumina
dispersion strengthened copper strips have been studied on both macroscopic
and microscopic scales. The textures of the rolled state were characterized
by ß-fiber, which runs from the Copper orientation {112}<111>
over the S orientation {123}<634> to the Brass orientation
{011}<211> in the Euler orientation space, with the intensities in the
S and the Brass components being higher that the Copper component. The Brass
component was attributed to a high strain hardening rate of the alloy. When
annealed at 1123K, the rolled specimens underwent recrystallization, with
recrystallization texture being approximated by {112}<312>. At the
initial stage of annealing, {hk0}<001> oriented grains are also
emerged but their growth stagnated. The recrystallization texture seems to
originate from the superposition of the S component {123}<634> and
{236}<385>, which are originated from the S and the Brass components
respectively in the deformed state. The large particles did not play an
important role in determining the rolling and the recrystallization
textures.
115.
Kim, S.-H., U. Erb, et al. (2002). Effect of Texture on the Corrosion
Behaviour of High Purity Aluminum. ICOTOM 13, Seoul, Korea, Trans Tech
Publications Inc.
The phenomenon of corrosion band formation found in recrystallized high
purity (99.9999%) Al in vol% HCl was investigated by correlating corrosion
initiation with local texture and grain boundary character distribution. It
is observed that bands with predominantly cube oriented grains and high
frequencies of low-angle boundaries show considerable resistance to
corrosion. Conversely, bands with a more random texture and large fractions
of high-angle boundaries are readily attacked. The formation of the band
structure was traced back to the initial grain structure of the as-cast
material.
116.
Kim, S.-I., B.-C. Ko, et al. (2003). "Evolution of dynamic
recrystallisation in AISI 304 stainless steel." Materials Science and
Technology 19(12): 1648-1652.
The nucleation and development of dynamic recrystallisation (DRX) has been
studied via hot torsion testing of AISI 304 stainless steel. The DRX
behaviour was investigated with microstructural analysis and slope changes
of flow stress curves. The characteristics of serrated grain boundaries
observed by SEM, electron backscattered diffraction and TEM indicated that
the nucleated DRX grain size was similar to that of the bulged part of the
original grain boundary. The DRX of the alloy was nucleated and developed by
strain induced grain boundary migration and by the necklace mechanism.
Before the steady state in the flow curve at 1000 deg C and 0.5
s-1, the dynamically recrystallised grains did not remain a
constant size and gradually grew to the size of fully DRX grains at steady
state (30 mu m). The calculation of the grain size was based on
XDRX (volume fraction of dynamically recrystallisation) under the
assumption that the nucleated DRX grains grow to the steady state
continuously. It was found that the calculated grain size of the alloy was
good agreement with that of the observed grain size. It is expected that a
fine grained steel can be obtained by controlling hot deformation conditions
on the basis of newly developed equations for predicting DRX
behaviour.
117.
Kim, S.-J., C.-S. Oh, et al. (2005). "Communications: Limit of ferrite
grain refinement by severe plastic deformation of austenite."
Metallurgical and Materials Transactions A 36(4): 1057-1060.
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.
118.
Kim, T., K. T. Hong, et al. (2003). "The relationship between the
fracture toughness and grain boundary character distribution in
polycrystalline NiA." Intermetallics 11(1): 33-39.
This paper reports the results of experimental studies on the relationship
between grain boundary character distribution and the fracture toughness in
the polycrystalline NiAl. The fracture toughness has been investigated by
the ring on ring disk bend test in conjunction with the acoustic emission
(AE) measurement, and the grain boundary character distribution is measured
by the electron back-scatter diffraction pattern (EBSD or EBSP) technique.
The fracture toughness of the annealed specimen (1473 K, 20 h) is 6.42
± 0.88 (MPa m-½) and that of the forged (1473 K)
and annealed (1473 K, 20 h) specimen is 5.08 ± 0.36 (MPa
m-½). The strong boundary and weak boundary were decided
by comparing the distribution of grain boundary characteristics at the
intergranular cracks to the distribution in general population. Σ1,
Σ3 and Σ 5 boundaries have strong and the good crack resistance,
but Σ7, Σ11, Σ13, Σ21 and Σ23 boundaries are
relatively weak boundary in the polycrystalline NiAl. Consequently, the
annealing process makes the fraction of Σ1 and Σ5 boundaries
higher than forging and annealing process. The high fraction of Σ1 and
Σ5 boundaries that have the good crack resistance seem to affect the
increase of fracture toughness in the annealed specimen.
119.
Kim, T.-W., N. Matsuki, et al. (2006). "Epitaxial growth of AlN on
single-crystal Ni(111) substrates." Applied Physics Letters
88(12).
We grew AlN thin films on Ni(111) at room temperature using pulsed laser
deposition. In situ reflection high-energy electron diffraction observations
showed sharp streak patterns, revealing that the AlN films grew epitaxially
and were of high quality, even when grown at room temperature. Electron
backscatter diffraction measurements showed that the in-plane epitaxial
relationship between the film and Ni was AlN[11-20]||Ni[01-1] with no
30° rotational domains. Grazing incidence angle x-ray reflectivity
measurements determined that the interfacial layer was less than 1.2 nm
thick, if present. This indicates that the heterointerface between the AlN
film and Ni substrate is atomically abrupt and that the AlN films serve as
an excellent barrier layer for Ni atoms. Furthermore, the refractive index
of a 60-nm-thick AlN film was 2.15 at 3.1 eV and 2.08 at 1.6 eV. These
results demonstrate that the AlN films grown on Ni substrates at room
temperature are of high quality from the perspective of their structural and
optical properties.
120.
Kim, W. J., C. W. An, et al. (2002). "Mechanical properties and
microstructures of an AZ61 Mg Alloy produced by equal channel angular
pressing." Scripta Materialia 47: 39-44.
The negative slope of yield stress versus d-½
in ECAPed AZ61 alloys can be explained by the gradual transition of the
texture during repetitive equal channel angular pressing (ECAP) to control
the grain size. Electron backscatter diffraction results of the present
study show that texture modification occurs during ECAP.
121.
Kim, W. W., G. H. Lee, et al. (2003). Study of phase transformation of nano
Al2O3 compacts derived by hydrolysis and subsequent
thermal sintering of Al powders. Designing, Processing and Properties of
Advanced Engineering Materials: Proceedings on the 3rd International
Symposium on Designing, Processing and Properties of Advanced Engineering
Materials, Jeju Island, South Korea.
Al2O3 compacts with various phases were prepared by
hydrolysis and spark plasma sintering (SPS) process of Al powder. The
bayerite (β-Al(OH)3) phase was derived by hydrolysis of
commercial Al powder with micron size, whereas the bohemite (AlO(OH)) phase
was obtained by hydrolysis of nano Al powder synthesized by pulsed wire
evaporation (PWE) method. Compaction as well as dehydration of both bayerite
and bohemite was carried out simultaneously by SPS method, which is used to
fabricate nano powder into dense compacts with a rapid heating rate of about
100nm chip)- C per min. under the pressure of 50 MPa. After compaction in
the temperature ranges from 350 Cu in tu C to 1100s.d EBSD C, the bayerite
and bohemite phases change into various alumina phases depending on the
compaction temperatures. The bayerite shows the phase transition of
Al(OH)3 →-Al2O3
θ-Al2O3 →
α-Al2O3 sequences. On the other hand, the
bohemite experiences the phase transition from AlO(OH) to
γ-Al2O3 at 350 AR passag C showing AlO(OH)
→ γ-Al2O3→
γ-Al2O3 → 9-Al2O3
→ α-Al2O3 sequences.
122.
Kim, Y. J., D.-W. Kim, et al. (2003). "Study on the non-linear property
of abnormally grown grain ZnO." Materials Chemistry and Physics
82(2): 410-413.
Abnormally grown large size ZnO grains were prepared by applying a specific
uniaxial pressure on the additive-free ZnO compact specimen. The average
grain size was larger than 500 µm after heat treatment at 1490 degrees
C for 4 h in air atmosphere. The crystallographic examination was performed
using X-ray diffraction (XRD) and electron back scatter diffraction (EBSD)
and the current-voltage characteristics were measured with the aid of
microscopic probes. These additive-free ZnO grains showed non-linear
current-voltage characteristics especially at a high current region. From
the several experimental results, we found the origin of the non-linearity
can be attributed to the presence of stress within grains which is
introduced during the growth procedure.
123.
Kimura, T., H. Kitahara, et al. (2004). Structure of martensite transformed
from severely deformed austenite in Fe-28.5at.%Ni. Ultrafine Grained
Materials III, Charlotte, North Carolina, USA.
Grain refinement of bulk materials by the SPD process followed by martensite
transformation was investigated. Fe-28.5at.%Ni alloy sheets were severally
deformed in austenite structure by the ARB process, and then cooled down to
77 K to cause martensite transformation. The ARB processed sheets deformed
to 4.0 of total equivalent strain were filled with the ultra-fine lamellar
boundary structure having about 200 run of average lamellar spacing.
Martensite transformation starting temperature decreased with increasing the
total equivalent strain. Martensite having characteristic morphologies
appeared from the ultra-fine lamellar austenite in the sheet ARB processed
by 5 cycles, although martensite transformed from conventionally
recrystallized specimens with several tens micrometers of grain sizes showed
typical plate (lenticular) morphology. It was concluded that the grain
refinement by martensite transformation from ultrafine grained austenite is
possible but low-angle boundaries in the austenite are not effective for
refinement by martensite transformation.
124.
King, W. E., J. S. Stolken, et al. (2000). Strategies for Analyzing EBSD
Datasets. Electron Backscatter Diffraction in Materials Science. A. J.
Schwartz, M. Kumar and B. L. Adams. New York, Kluwer Academic/Plenum
Publishers: 153-65.
125.
Kitahara, H., R. Ueji, et al. (2006). "Crystallographic features of
lath martensite in low-carbon steel." Acta Materialia 54(5):
1279-1288.
Electron backscattering diffraction with field-emission scanning electron
microscopy was used to analyze crystallographically the lath martensite
structure in a 0.20% carbon steel. The crystallographic features of the lath
martensite structure, of the order of the prior austenite grain size or
larger, were clarified. Although the orientations of the martensite crystals
were scattered around the ideal variant orientations, the martensite in this
steel maintained the Kurdjumov–Sachs (K–S) orientation
relationship. The procedures of the crystallographic analysis of the
martensite (ferrite) phase with the K–S orientation relationship were
explained in detail. Variant analysis showed that all 24 possible variants
did not necessarily appear within a single prior austenite grain and that
all six variants did not necessarily appear within each packet. Specific
combinations of two variants appeared within local regions (sub-blocks),
indicating a strict rule for variant selection. Prior austenite grain
boundaries and most of the packet boundaries were clearly recognized.
However, it was difficult to determine the block boundaries within the
sub-blocks.
126.
Kitahara, H., Y. Minamino, et al. (2005). "Crystallographic analysis of
plate martensite in Fe-28.5 at.% Ni by FE-SEM/EBSD." Materials
Characterization 54(4-5): 378-386.
Crystallographic analysis of plate martensite in an Fe-28.5 at.% Ni alloy
was studied by electron backscattering diffraction (EBSD) in a scanning
electron microscope equipped with a field emission gun (FE-SEM). It was
shown that sound orientation mapping was possible even for the martensite
having a high density of lattice defects and the FE-SEM/EBSD could be a
strong tool for crystallographic/microstructural analysis of martensite in
steels. It was confirmed that the martensite in this alloy held the
Nishiyama-Wassermann (N-W) orientation relationship. Variant analysis of
every martensite crystal was successfully done from orientation mapping
data. It was clarified that a certain rule of variant selection operated
within local areas. The procedures of crystallographic analysis of N-W
martensite were explained in detail.
127.
Kitamura, T., T. Sumigawa, et al. (2004). "Slip Behavior and Local
Stress near Grain Boundary in High-Cycle Fatigue of Copper
Polycrystal." JSME International Journal, Series A 47(2):
92-97.
Recent development of OIM (Orientation Imaging Microscope) makes the
measurement of crystal orientation easy and advanced computer technology
allows us to conduct a detailed stress analysis of component with
microstructure. In this study, a high-cycle fatigue test was carried out for
a copper polycrystal, where the shape and orientation of each grain is
measured by the OIM Thirteen PSBs are found along the grain boundaries, and
the location and slip system are different from those expected by the Schmid
factor. FEM analysis is conducted for the copper polycrystal with the same
orientation and shape. It reveals that the increase of resolved shear
stress, Trss, of specific slip system due to the constraint of deformation
between grains causes the unique slip behavior near the grain boundary.
128.
Klöden, B., E. Rybacki, et al. (2005). "Torsional creep of
polycrystalline NiAl." Scripta Materialia 52(4):
289-293.
Polycrystalline NiAl has been deformed in torsion to large strains at
temperatures between 800 K and 1300 K. The deformation curves indicate
continuous dynamic recrystallization and strain weakening. If applying a
conventional power law rheology to the data the activation energy and the
stress exponent decrease with increasing stress and/or temperature. A model
based on cross-slip of screw dislocations is proposed as the creep mechanism
for steady state creep.
129.
Klöden, B., W. Skrotzki, et al. (2005). Dynamic recrystallization of
torsion deformed NiAl. Textures of Materials - ICOTOM 14, Leuven, Belgium,
Trans Tech Publications.
Polycrystalline samples of NiAl have been deformed in torsion in the
temperature range 800K - 1300K. Deformation is accompanied by dynamic
recrystallization, which with increasing temperature changes from continuous
to discontinuous mode. Emphasis was put on the occurrence of dynamic
recrystallization, which will be discussed with respect to texture and
microstructure.
130.
Kleber, S., R. Pippan, et al. (2004). Microstructure of austenitic and
ferritic steels produced by severe plastic deformation and subsequent
annealing. Ultrafine Grained Materials III, Charlotte, North Carolina,
USA.
An austenitic steel and a ferritic steel are subjected to Severe Plastic
Deformation (SPD) at room temperature (similar to 0.16Tm) followed by
subsequent annealing. The aim of this materials processing is the refinement
of the initially coarse microstructure. The microstructural change during
SPD as a function of applied plastic strain (maximum 32) and different
annealing parameters is analyzed for both steels by Back Scattered Electrons
micrographs captured in a Scanning Electron Microscope (SEM). Additionally
the microtexture of selected samples is measured by the automated Electron
Back Scattering Diffraction method within a SEM. The size of the structural
elements in the SPD state is clearly below 100nm. Appropriate thermal
treatments transform these metastable deformation microstructures into more
stable microstructural elements with sizes smaller than 500nm.
131.
Klein, H., A. Preusser, et al. (2004). Recrystallization Texture and
Microstructure in Ni and AlMg1Mn1 Determined with High-Energy Synchrotron
Radiation. Second Joint International Conference on Recrystallization and
Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications
Ltd.
132.
Kleinschrodt, R. and J. P. Duyster (2002). "HT-deformation of garnet:
an EBSD study on granulites from Sri Lanka, India and the Ivrea Zone."
Journal of Structural Geology 24(11): 1829-1844.
Garnets from three regional granulite terrains (Sri Lanka, Eastern Ghats,
Ivrea Zone) have been analyzed and the results indicate, that garnet can be
plastically deformed by dominant dislocation glide/creep with variable
dominant slip systems.
Garnets from a granulite facies fold hinge in a quartzite of the Highland
Complex of Sri Lanka, unequivocally attest to plastic deformation of garnet.
Outside the fold hinge the garnets form flat discs elongated parallel to a
pronounced stretching lineation and show deformation microstructures like
boudinage and pinch and swell structures. In the fold hinge these garnet
discs are folded within the quartzitic matrix at temperatures of about 800
°C. In spite of the preservation of deformed shapes, intracrystalline
deformation microstructures are scarce. The garnets have distinct
crystallographic preferred orientations, which can be interpreted by a
dominant 1/2111{110} slip system approaching ‘easy slip’
positions. These are reached rapidly under moderate strains as necessary
lattice rotations are small.
Similar slip systems were derived for a garnet-bearing quartzite from the
Eastern Ghats deformed at temperatures of 750–800 °C, but with
more influence of initial orientation of garnets. Completely different
textures indicative of dominant 100 [010] slip were found in a restitic
garnet–sillimanite granulite from the Ivrea Zone. The variable
deformation features and variable slip systems with 1/2111 and 100 Burgers
vectors prove that garnets bear significant potential for contributing
additional information on the HT-deformation of rocks.
133.
Klepeis, S. J., J. P. Benedict, et al. (1988). "A Grinding/Polishing
Tool for TEM Sample Preparation." Materials Research Society Symposium
Proceedings 115: 179-183.
134.
Kliauga, A. M. and M. Ferrante (2005). "Liquid formation and
microstructural evolution during re-heating and partial melting of an
extruded A356 aluminium alloy." Acta Materialia 53(2):
345-356.
Thixoforming processes require feedstock having a non-dendritic, equiaxed
microstructure, which in some cases can be obtained by a deformation-
recrystallisation technique followed by partial melting. From the study of
an extruded, re-heated and partially re-melted A356 alloy, a number of
phenomena were observed and analysed: grain and particle growth, texture and
low angle grain boundary formation, primary phase coarsening during
isothermal holding in the semi-solid state and uneven distribution of Si
particles and liquid phase. Both grain growth (solid state) and particle
growth (semi-solid state) obey a R3 against time relationship. It was also
found that microstructural coarsening follows an Ostwald ripening type of
growth and that coalescence was also present, although exerting a minor
role. Finally, phenomena such as the evolution with time of the proportion
of low angle grain boundaries, and the relationship between
recrystallisation, the onset of liquid formation and the coarse Si particle
precipitation and dissolution are presented and discussed.
135.
Klimanek, P., V. Klemm, et al. (1991-?). "Disclinations in plastically
deformed metallic materials." Advanced Engineering Materials
3(11): 877-884.
Cold-working of metallic materials up to large strains is usually
characterised by simultaneous substructure evolution on different length
scales and accompanied by the formation of significant lattice rotations. A
promising tool for the description of such microstructure development is the
concept of partial disclinations. Transmission electron microscopy (TEM)
studies illustrate clearly that defects of this kind are frequently existent
in cold-worked metals and have to be accepted as an important defect entity
in the substructure evolution at larger strains. Moreover, it is shown that
substructure modelling on the base of a coupled dislocation-disclination
dynamics leads to satisfying correspondence of calculated substructure
characteristics with experimental results obtained by TEM, X-ray
diffractometry, and EBSD (electron backscattering diffraction), and to a
satisfying prediction of the macroscopic deformation behaviour, i.e.,
especially the transition from stage III to stage IV of crystal plasticity.
(Example materials: Fe, Cu, Ti.)
136.
Klimanek, P., V. Klemm, et al. (2004). "Substructure analysis in
heavily deformed materials by diffraction methods." Advanced
Engineering Materials 6(11): 861-871.
Plastic deformation of metallic materials up to large strains is, in many
cases, characterised by the activation of different deformation modes and
the formation of complicated, locally inhomogeneous substructures, which
give rise to both significant lattice strains and rotations. A suitable tool
for the investigation of the microstructures is a combination of diffraction
techniques as, for instance, electron microscopy (TEM; EBSD) and X-ray
diffractometry. In order to demonstrate the potential of the diffraction
analysis the following procedures are considered: Evaluation of radial and
azimuthal broadening of X-ray diffraction peaks, EBSD analysis of block
structures, and TEM identification of disclination arrangements in
compressed Fe-Si and Ni single crystals.
137.
Klimek, L. and B. Pietrzyk (2003). Electron backscatter diffraction as a
useful method for alloys microstructure characterization. Proceedings of the
European Materials Research Society, Warsaw, Poland, Elsevier B.V.
Microstructure examination of cast Co-Cr-Mo alloy is presented in this
paper. The surface morphology and chemical composition of the alloy were
investigated by means of scanning electron microscopy (SEM) and energy
dispersive X-ray microanalysis (EDX). An identification of alloy phases was
carried out using electron backscatter diffraction (EBSD). Two different
kinds of precipitates in metallic matrix were found. They were identified as
MC and M23C6 type of carbides in Co-lattice solid
solution. The advantages and limits of the EBSD method are described. It is
presented that EBSD, as excellent tool for phase identification, is a
valuable supplementary method for materials research. Copyright 2004
Elsevier B.V. All rights reserved.
138.
Kloss, N. and P. Paufler (1984). "On the Relation Between Kossel Line
Broadening and Dislocation Density." Crystal Research and Technology
19(3): K30-K34.
139.
Kluken, A. O., Ø. Grong, et al. (1991). "The Origin of
Transformation Textures in Steel Weld Metals Containing Acicular
Ferrite." Metallurgical Transactions A 22(March):
657-663.
140.
Knorr, D. B. (1993). "The Role of Texture on the Reliability of
Aluminum-Based Interconnects." Materials Research Society Symposium
Proceedings 309: 75-86.
141.
Knorr, D. B. and K. P. Rodbell (1996). "The role of texture in the
electromigration behavior of pure aluminum lines." Journal of Applied
Physics 79(5): 2409-2417.
142.
Knorr, D. B., H. Weiland, et al. (1994). "Overview: Applying Texture
Analysis to Materials Engineering Problems." JOM 46(9):
32-6.
143.
Knowles, D. M. and S. Gunturi (2002). "The role of <112>{111}
slip in the asymmetric nature of creep of single crystal superalloy
CMSX-4." Materials Science and Engineering A 328:
223-237.
A number of slip systems are known to operate in commercial Ni-base single
crystal superalloys, one of these being the {111} <112> system which
is particularly influential in the primary creep regime. The asymmetric
nature of this dislocation activity with regard to the direction of slip
under creep conditions is highlighted in this paper. Testing has been
undertaken on CMSX-4 at temperatures of 1223 and 1023 K. The [001] and [256]
orientations have been investigated under tensile and compressive loading
conditions. It has been demonstrated that in addition to stacking fault
generation, twinning of the complete two-phase structure is a major source
of creep strain accumulation under certain conditions. These are dependent
upon activation of suitable a/3,<112>{111} partials which are a
function of the sign of the resolved shear stresses. TEM analysis and EBSD
measurements have shown that twin nucleation is dependent upon the
activation of suitable <110>{111} type slip within the matrix
channels, but once it has taken place deformation can proceed rapidly, only
being hindered if a suitable network of dislocations within the matrix
channels can be created to halt the progress of the twinning
partials.
144.
Knutsen, R. D., F. J. Humphreys, et al. (1999). Texture stability during
high temperature plane strain compression of a commercial Al-Mg alloy.
Twelfth International Conference on Textures of Materials (ICOTOM 12),
McGill University, Montreal, Canada, NRC Research Press.
145.
Kobayashi, M., T. Yoshimasa, et al. (2002). Prediction of Texture
Development during Grain Growth in Pure Alminum by Monte Carlo Simulation.
ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The modified Monte Carlo (MC) simulation of grain growth has been performend
in the model applying practical orientation data to an initial
microstructure. The experimental sample used in SEM/EBSP analysis was
annealed sheet and foil of a pure aluminum after rolling. It was found that
the samples of a pure aluminum had a general recrystallization texture in a
rolled sheet. The texture became sharper during grain growth. The simulation
was carried out using modified MC method by considering activated states for
grain-boundary migration. The texture developed having analogy with that of
experiment for the model with dependence of grain-boundary energy on
crystallographic misorientation, while the texture was randomized for the
basic model without the dependency.
146.
Kobayashi, M., Y. Takayama, et al. (2004). "Preferential growth of
cube-oriented grains in partially annealed and additionally rolled aluminum
foils for capacitors." Materials Transactions 45(12):
3247-3255.
It is well known that a sharp cube texture is developed for the producing
process of a pure aluminum foil for capacitors. The orientation analysis
using scanning electron microscopy/electron backscattered diffraction
pattern (SEM/EBSP) method has been performed on the transverse direction
(TD) sections impartially annealed (PAed) and additionally rolled (ARed)
foils through the thickness in order to reveal how cube-oriented grains have
advantages for growth in comparison with the other grains with orientation
components of rolling texture. Samples were annealed repeatedly with
increasing the temperature in a vacuum. The cube grains were distributed
throughout foil thickness homogeneously in the PAed and ARed foils. The main
mechanism of preferential growth of the cube grains in the PAed foils was
driven by grain boundary energy. However, the growth for ARed foils was
caused by strain induced grain boundary migration (SIBM) driven by the
difference in stored energy between the cube and the other grains, because
the former store less strain energy than the latter after the additional
rolling. Furthermore, the grown-up cube grains having similar orientations
met each other and made a cluster in both the foils. Since the clusters
develop to reach the foil surfaces and become stable, the cube grains are
easy to cover all of the foil in the final stage of annealing.
147.
Kobayashi, S., S. Zaefferer, et al. (2004). Effect of the Degree of Order
and the Deformation Microstructure on the Kinetics of Recrystallisation in a
Fe3Al Ordered Alloy. Second Joint International Conference on
Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France,
Trans Tech Publications Ltd.
A Fe3Al based single phase alloy was rolled at 600°C and
400°C and the kinetics of recrystallisation in A2 and B2 phase regions
was determined in conjunction with the kinetics of the A2-B2 ordering and
recovery. At 700°C and 800°C the recrystallisation kinetics depends
strongly on the temperature of rolling while at 900°C only a small
influence is visible. These results are attributed to the high stored energy
in the sample rolled at 400°C and its high recovery rate at 900°C,
leading to a similar level in stored energy as for the sample rolled at
600°C in the beginning of annealing. At lower temperatures, in contrast,
the difference in stored energy is conserved over longer times in the
annealing process.Almost half the apparent activation energy was observed in
the ordered state compared to that in the disordered state.
148.
Kobayashi, S., S. Zaefferer, et al. (2004). "Slip system determination
by rolling texture measurements around the strength peak temperature in a
Fe3Al-based alloy." Materials Science and Engineering A
387-389: 950-954.
Texture measurements were carried out on a Fe–26Al–5Cr alloy
that was deformed by warm rolling at temperatures above and below the stress
anomaly temperature in order to obtain information about a possible change
of slip systems around that temperature. Special attention was paid to the
initial microstructure, temperature during rolling and recrystallisation
problems. Textures were determined by automatic crystal orientation mapping
(ACOM) using electron backscatter diffraction (EBSD), which allows
separation of measurement data from recrystallised and unrecrystallised
fractions in the microstructure. A clear difference in texture evolution
appears above and below the stress anomaly temperature; the most preferred
orientations after rolling at 600 and 400 °C are ~{5 5 7}<1 1 0>
and ~{1 1 1}<2 1 1>, respectively. This result suggests that the shear
fraction of the active {1 1 2}<1 1 1> slip systems increases with
respect to that of the {1 1 0}<1 1 1> slip systems with increasing
temperature around the stress anomaly temperature.
149.
Kobayashi, S., S. Zaefferer, et al. (2005). Carbide Precipitation in an
Fe3Al-Cr-Mo-C Alloy. Solid to Solid Phase Transformations in
Inorganic Materials 2005, Phoenix, Arizona, USA, TMS.
Carbide precipitation within α-(A2/B2) matrix has been studied in a
Cr, Mo and C doped Fe3Al-based alloy by high resolution scanning
microscopy, electron backscattered diffraction and energy dispersive
spectrometry. The sequence of carbide precipitation is
$kappa@-Fe3AlC (E21) → M2C
(B81) → M7C3 (D101) at
1273K. and $kappa@-Fe3AlC (E21) → M2C
(B81) → M7C3 (D101) →
M6C (E93) at 1073K and 973K (The symbols in
parentheses refer to Structurbericht designation). The $kappa@-carbide is
metastable at all the temperatures. The M2C carbide disappears
during annealing at all the temperatures, but it re-precipitates with higher
Mo and lower Cr concentration below 1073K. The M7C3
precipitates by separate nucleation within the a matrix, whereas the
M6C carbides nucleate preferentially at the interface between
α/M7C3, growing mainly into the matrix. The
sequence of carbide precipitation is in accordance with the order of
descending (Mo+Cr)/C ratios of the carbides.
150.
Koblischka-Veneva, A. and F. Mücklich (2002). "Orientation imaging
microscopy applied to BaTiO3 ceramics." Crystal Engineering
5: 235-242.
By means of orientation imaging microscopy, we have investigated grain
orientation distributions of various BaTiO3ceramic samples
prepared using different preparation routes. We present details of the
required surface preparation steps in order to enable an automated
orientation mapping. The samples are characterized by image quality (IQ),
grain size (GS) and grain orientation (IPF) maps. Finally, the grain
orientation distribution functions are obtained from the measured data. It
is shown that the samples do not exhibit any preferred grain
orientations.
151.
Koblischka-Veneva, A. and M. R. Koblischka (2002). Characterization of bulk
superconductors through EBSD methods. Proceedings of the 15th International
Symposium on Superconduc, Yokohama, Japan.
The application of electron backscatter diffraction (EBSD) technique to bulk
high-Tc superconductors is presented and reviewed. Due to the
ceramic nature and the complex crystallographic unit cells of the
perovskite-type high-Tc superconductors, the EBSD analysis is not
yet as common as it deserves. We have successfully performed EBSD analysis
on a variety of high-Tc compounds and samples including
polycrystalline YBCO (pure and doped by alkali metals), melt-textured YBCO,
thin and thick films of YBCO; the "green phase"
Y2BaCuO5, thin film and melt-textured
NdBa2Cu3Ox and Bi-2212 single crystals and
tapes. It is shown that the surface preparation of the samples is crucial
due to the small information depth (up to 100 nm) of the EBSD technique.
High quality Kikuchi patterns are the requirement in order to enable the
automated EBSD mapping, which yields phase distributions, individual grain
orientations and the misorientation angle distribution. The results can be
presented in form of mappings, as charts, and as pole figures. These
informations are required for a better understanding of the growth
mechanism(s) of bulk high-Tc superconductors intended for
applications.
152.
Koblischka-Veneva, A. and M. R. Koblischka (2003). "Texture analysis of
melt-textured and polycrystalline YBa2Cu3Oy
using EBSD." Journal of Low Temperature Physics 131(3-4):
653-658.
We applied an electron backscatter diffraction (EBSD) technique to determine
the texture and individual crystallite orientations on melt-textured and
various polycrystalline YBa2 Cu3 Oy (YBCO)
samples, doped with several Alkali metal additions (KCIO3,
K2CO3 and Rb2 CO3). The EBSD
analysis on melt-textured YBCO reveals a direct interplay between the
crystal orientations of YBCO and the Y2BaCuO5 (Y-211)
particles. The Y-211 particles do not show any texture, but certain
orientations of the Y-211 particles enable an homogeneous growth of YBCO.
From the measured data, individual misorientations and the orientation
distribution functions are obtained for all samples studied.
153.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2002). Position-dependent
texture analysis of melt-textured YBCO by means of electron backscatter
diffraction. Proceedings of the 15th International Symposium on Superconduc,
Yokohama, Japan.
The texture and phase distribution of melt-textured
YBa2Cu3Ox(YBCO) was studied by means of
automated electron backscatter diffraction (EBSD) analysis as a function of
the position in the bulk pellet of 4 cm diameter. A total of five samples
was cut from the pellet; four samples from the surface of the bulk with
different distances to the seed crystal, and one cut in vertical direction
in the middle of the pellet. The melt-textured YBCO samples require a
two-phase analysis to be performed, so a high surface quality is necessary
to enable an automated EBSD scan. Good quality Kikuchi patterns are obtained
from both the 1 2 3 and 2 1 1 phases. We found an inhomogeneous distribution
of the 2 1 1 particles. Whereas the samples cut from the surface contain a
large amount of 211 particles, in the samples of the vertical direction only
traces of 2 1 1 particles are found. Furthermore, we measured the
misorientation angle distribution of all samples. The data are presented in
form of phase mappings, misorientation distribution functions and pole
figures.
154.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2002). Orientations of
Y2BaCuO5 and YBCO within melt-textured and directional
solidified samples studied by EBSD. Proceedings of the 15th International
Symposium on Superconduc, Yokohama, Japan.
By means of automated electron backscatter diffraction (EBSD) analysis, we
studied the local orientations of embedded Y2BaCuO5 (2
1 1) particles within melt-textured YBCO samples, and also the orientations
of embedded YBCO particles in directional solidified 211 samples. On both
systems, we obtained high-quality Kikuchi patterns, allowing the automated
mapping of the crystal orientations and a multi-phase analysis. In
melt-textured YBCO with (0 0 1) orientation, we find that the embedded 211
particles do not have any preferred orientation, but the maps also reveal
that at certain orientations of the 211 particles the YBCO growth is not
altered. In directional solidified 211 samples, where the 211 is mainly
oriented in (0 0 1) direction, the embedded YBCO particles show only some
specific orientations. Copyright 2003 Elsevier B.V. All rights
reserved.
155.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2002). Texture analysis of
melt-textured YBCO superconductors. Proceedings of the 15th International
Symposium on Superconduc, Yokohama, Japan.
We compare the results of an X-ray based pole figure texture analysis with
the local texture analysis by means of electron-backscatter diffraction
(EBSD) analysis. As samples, we employ two different melt-textured YBCO
samples; one fully processed and one without oxygen treatment. To enable the
direct comparison of the two techniques, we employ the 103 pole figures. We
find a clear coincidence between the results obtained by the two measurement
techniques on our samples, however, the EBSD results are much more detailed,
yielding the local grain orientation distribution and quantitative results
of the grain or subgrain misorientation angles. Therefore, the EBSD
measurements give information not accessible to the X-ray pole figure
analysis. The surface preparation procedure is essential to enable the
automated EBSD mapping as high image quality Kikuchi patterns are required.
The polishing procedures are discussed in detail.
156.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2002). "Orientation
imaging microscopy analysis of bulk, melt-textured YBCO
superconductors." Crystal Engineering 5: 265-272.
In this contribution, we apply orientation imaging microscopy (OIM) to
melt-textured, bulk YBa2Cu3Oy (YBCO)
samples, which require to perform an automated two-phase analysis. Both YBCO
and the green phase Y2BaCuO5 (Y-211) are of
orthorhombic crystal structures, but with clearly distinct unit cell
parameters. We obtain the orientations of the individual crystallites and
the misorientation distributions for both YBCO and Y-211. From the obtained
data, we calculate the orientation distribution functions.
157.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2002). "Orientation
imaging microscopy analysis of bulk, melt-textured YBCO
superconductors." Crystal Engineering 5: 265-272.
In this contribution, we apply orientation imaging microscopy (OIM) to
melt-textured, bulk YBa2Cu3Oy (YBCO)
samples, which require to perform an automated two-phase analysis. Both YBCO
and the green phase Y2BaCuO5 (Y-211) are of
orthorhombic crystal structures, but with clearly distinct unit cell
parameters. We obtain the orientations of the individual crystallites and
the misorientation distributions for both YBCO and Y-211. From the obtained
data, we calculate the orientation distribution functions.
158.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2002). "Electron
backscatter diffraction study of polycrystalline
YBa2Cu3O7-δ
ceramics." Physica C 382(2-3): 311-322.
The electron backscatter diffraction (EBSD) technique was applied to
polycrystalline
YBa2Cu3O7-δ ceramics. To
obtain good quality EBSD Kikuchi patterns on the ceramic superconductors, a
new sample polishing route was established. Samples with and without
KClO3-doping were investigated; and the crystallographic
orientations of the grains were analyzed using pole figures and EBSD
orientation mapping. On the polycrystalline KClO3-doped
YBa2Cu3O7-δ samples we
found two major orientations (0 0 1) and (1 0 0) normal to the sample
surface, while the undoped sample did not exhibit any orientation maxima. We
ascribe this observation to the effect of a liquid phase due to the
KClO3-additive during the preparation process.
159.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2004). Orientation of
embedded Y2BaCuO5 particles within the
YBa2Cu3Ox matrix in melt-textured YBCO
superconductors. NATO Advanced Research Workshop Advanced Materials for
Radiation Detectors and Sensors: Wide-Gap Semiconductors and Superconductors
and E-MRS 2004 Fall Meeting Symposium E, Warsaw, Poland, Wiley-VCH.
Automated electron backscatter diffraction (EBSD) was employed to study the
local orientations of embedded Y2BaCuO5 (Y-211)
particles within the YBa2Cu3Ox (Y-123)
superconducting matrix of large grain, melt-textured Y-Ba-Cu-O (YBCO)
samples. High-quality Kikuchi patterns were obtained, enabling automated
mapping of the individual crystal orientations and a two-phase analysis of
the samples. Investigations were performed on a variety of melt-textured
YBCO samples, including samples with different element additions. We observe
from the maps that the embedded Y-211 particles do not have any preferred
orientation in melt-textured YBCO with (001) orientation, and that the YBCO
growth is not altered for certain orientations of the Y-211 particles. In
samples with (100) orientation, on the other hand, we observe only a small
misorientation within the YBCO matrix, and the embedded Y-211 particles do
not exhibit any texture. We can conclude from the EBSD maps obtained that
the formation of small Y-211 particles does not disturb the Y-123 matrix
growth, whereas the presence of large Y-211 particles leads, significantly,
to the formation of subgrains
160.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2004). OIM and X-ray
texture analysis of melt-textured YBCO superconductors. NATO Advanced
Research Workshop Advanced Materials for Radiation Detectors and Sensors:
Wide-Gap Semiconductors and Superconductors and E-MRS 2004 Fall Meeting
Symposium E, Warsaw, Poland, Wiley-VCH.
The results of two independent texture measurements on melt-textured
Y-Ba-Cu-O (YBCO) high-Tc superconductors are compared with each
other. The texture data are acquired by means of an X-ray based pole figure
texture analysis and of a local texture analysis provided by an automated
electron-backscatter diffraction (EBSD) or often called orientation imaging
microscopy (OIM) analysis. As samples, we employ two different melt-textured
YBCO samples; one fully processed (orthorhombic) and one without oxygen
treatment (tetragonal). Pole figures in Ý103¨ direction are used
to enable a direct comparison. We find a clear coincidence between the
results obtained by the two measurement techniques on the melt-textured YBCO
samples, however, the EBSD results are much more detailed, yielding the
local grain orientation distribution and quantitative results of the grain
or subgrain misorientation angles. Therefore, the EBSD measurements give
informations which are not accessible by the X-ray texture analysis.
161.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2005). "Comparative
study of grain orientation in melt-textured HTSC with different
additions." Physica C 426-431: 618-624.
The local orientation of particles embedded within melt-textured Y-Ba-Cu-O
(YBCO) samples containing depleted uranium oxide,
Y2O3, Nb2O5, and
Y2Ba4CuMOx (with M=Nb, Zr) have been
studied via automated electron backscatter diffraction (EBSD) analysis. The
different morphologies of the samples are discussed based on the EBSD scans
of a-growth sector areas. We conclude that the formation of small, nanoscale
particles does not disturb the growth of the superconducting YBCO matrix.
The presence of large, micrometre-sized particles, however, may cause severe
changes in the YBCO growth morphology.
162.
Koblischka-Veneva, A., M. R. Koblischka, et al. (2005). "Interplay of
YBCO and embedded 211 particles in melt-textured YBCO superconductors."
Journal of Superconductivity 18(4): 469-474.
Local orientations of superconducting
YBa2Cu3Ox (123) and embedded
Y2BaCuO5 (211) particles within bulk, melt-textured
123 samples are studied on a local scale by means of electron backscatter
diffraction (EBSD). The embedded Y2BaCuO5 (211)
particles do not show any preferred texture, but their presence within the
123-matrix alters the growth of the 123-phase, independent of the
orientation. EBSD enables to analyse the interactions between the 123- and
211-phases in detail.
163.
Koblischka-Veneva, A., M. R. Koblishcka, et al. (2003). "A study of
grain orientation of Alkali doped polycrystalline YBCO ceramics using an
EBSD technique." Crystal Engineering 5(3-4, spec.):
411-418.
Polycrystalline KClO3-, K2CO3-,
Rb2CO3-doped and undoped
YBa2Cu3O7-x (YBCO) ceramic
high-Tc superconductors were examined using electron backscatter
diffraction (EBSD) technique. We present orientation maps and pole figures
of the samples. It is shown that the pure YBCO samples and the ones with
Rb2CO3 and K2CO3 additives do
not exhibit a very pronounced texture (i.e. preferred orientation). On the
polycrystalline KClO3-doped YBCO samples we find two major grain
orientations (0 0 1) and (1 0 0) normal to the sample surface while the pure
YBCO sample does not exhibit any orientation maxima. This observation is
ascribed to the effect of a liquid phase due to the
KClO3-additive during the preparation process.
164.
Kocks, U. F., S. I. Wright, et al. (1996). A Comparision of Different
Texture Analysis Techniques. Eleventh International Conference on Textures
of Materials (ICOTOM-11), Xi'an, China, International Academic:
Beijing.
165.
Kocks, U. F., S. I. Wright, et al. (1996). Deformation and Recrystallization
of Hot Deformed Aluminum with High Initial Cube Texture. Eleventh
International Conference on Textures of Materials, Xi'an, China,
International Academic Publishers.
166.
Koetter, T. G., H. Wendrock, et al. (2000). "Relationship between
microstructure and electromigration damage in unpassivated PVD copper
damascene interconnects." Microelectronics Reliability 40:
1295-1299.
167.
Kogtenkova, O. A., V. N. Semenov, et al. (2004). "Pokrovsky-talapov
critical behavior and rough-to-rough ridges of the Σ3 coincidence tilt
boundary in mo." Physical Review Letters 92(19):
196101-1--196101-4.
The as-grown shape of the cylindric tilt grain boundary (GB) in Mo
bicrystals grown by the floating zone method has been studied with the
electron backscattering diffraction method. The seed crystals were
misoriented such that the coincidence site lattice (CSL) with lowest
possible inverse density of coincidence sites, a Σ =3 was grown. The
flat (100) Sigma 3CSL facets were observed forming smooth edges
(no slope discontinuity) with rounded rough GB portions. Rough GBs curve
away from the plane of the (100) Sigma 3CSL facet as x/sup beta /
with beta =1.69+or-0.07 on one side and beta =1.72+or-0.07 on the other
side. Therefore, GB roughening belongs to the Pokrovsky-Talapov universality
class. Slope discontinuities between two rounded rough GB portions were also
observed. This is the first experimental observation of such first-order
rough-to-rough ridges predicted by the Davidson-den-Nijs model.
168.
Kogure, T. (2003). "A program to assist Kikuchi pattern analyses."
Journal of the Crystallographic Society of Japan 45(6):
391-395.
A program to draw and analyze Kikuchi patterns is introduced, especially for
electron back-scattering diffraction (EBSD) analysis that has become popular
recently. The functions of the program include geometrical drawing of
Kikuchi patterns with contrast from kinematical calculation, indexing of
observed patterns, acquisition of camera parameters, etc. except for
automated crystal orientation map measurement for polycrystalline materials.
The program is available from an Internet website and performed on a Windows
machine. The outline of the calculation methods in the program is described
briefly.
169.
Kohno, M., M. Muraki, et al. (2002). Deformation Microtexture and
Recrystallized Orientations in Non-Oriented Electrical Steel Observed by
High-Resolution EBSD. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
The texture evolution during recrystallization was investigated in cold
rolled 0.1% Si non-oriented electrical steel sheet. Both fine and
coarse-grained hot rolled steel sheets of 2.6mm thickness were cold rolled
by 42 to 81% reduction. They were subsequently heat-treated from 575°C
to 900°C for partial recrystallization, and the microtexture evolution
was observed. {111} recrystallized grains are frequently observed in
initially fine-grained specimens with high reduction. They nucleated near
original grain boundaries and its contribution became less important in
initially coarse-grained specimen. The initial stages of recrystallizations
were observed by high-resolution EBSD. Goss texture prevails in initially
coarse grained specimens regardles of the cold reduction. These Goss grains
nucleated mainly within {111}<112> oriented deformed grains along
in-grain deformation microbands.The microstructure was similar to those
reported for deformation bands in cold rolled single crystals with the same
orientation. Recrystallization mechanism was discussed in accordance with an
interpretation that the recrystallized nuclei is created by action of slip
systems and accumulation of dislocations.
170.
Koike, J., A. Sekiguchi, et al. "A Relationship between Film Texture
and Stress-Voiding Tendency in Copper Thin Films."
The origin of stress voiding in heat-treated Cu thin films was investigated
in relation to microstructure. Voids were observed at the intersections of
twins with grain boudaries or with other twins. Twin interfaces were
accompanied by stress concentration due to the elastic anisotropy. Stress
concentration was found to act as a driving force for stress voiding. Twin
formation and associated void formation could be avoided by controlling the
film texture. Texture transition from (111) to (100) was observed in
heat-treated films with increasing the film thickness from 200 nm to 300 nm.
The (100) oriented films did not show any voids or hillocks. The excellent
stress-migration resistance in the (100) oriented films could be attributed
to the absence of twins and by small thermal stresses.
171.
Koike, J., T. Miyamura, et al. (2005). The types and roles of deformation
twinning in AZ31 Mg alloys. 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.
172.
Kokawa, H. (2005). "Weld decay-resistant austenitic stainless steel by
grain boundary engineering." Journal of Materials Science 40:
927-932.
This paper presents an example of grain boundary engineering (GBE) for
improving intergranular-corrosion and weld-decay resistance of austenitic
stainless steel. Transmission and scanning electron microscope (TEM and SEM)
observations demonstrated that coincidence site lattice (CSL) boundaries
possess strong resistance to intergranular precipitation and corrosion in
weld decay region of a type 304 austenitic stainless steel weldment. A
thermomechanical treatment for GBE was tried for improvement of
intergranular corrosion resistance of the 304 austenitic stainless steel.
The grain boundary character distribution (GBCD) was examined by orientation
imaging microscopy (OIM). The sensitivity to intergranular corrosion was
reduced by the thermomechanical treatment and indicated a minimum at a small
roll-reduction. The frequency of CSL boundaries indicated a maximum at the
small roll-reduction. The corrosion rate was much smaller in the
thermomechanical- treated specimen than in the base material for long time
sensitization. The optimum thermomechanical treatment introduced a high
frequency of CSL boundaries and the clear discontinuity of corrosive random
boundary network in the material, and resulted in the high intergranular
corrosion resistance arresting the propagation of intergranular corrosion
from the surface. The optimized 304 stainless steel showed an excellent
resistance to weld decay during arc welding.
173.
Kokawa, H., M. Shimada, et al. (2005). Grain boundary engineering for
intergranular corrosion resistant austenitic stainless steel. Proceedings of
International Symposium on Phase Diagrams of Alloys and Microstructural
Control of Advanced Materials, China Shenyang.
Sensitization by chromium depletion due to chromium carbide precipitation at
grain boundaries in austenitic stainless steels can not be prevented
perfectly only by previous conventional techniques, such as reduction of
carbon content, stabilization-treatment, local solution-heat-treatment, etc.
Recent studies on grain boundary structure have revealed that the
sensitization depends strongly on grain boundary character and atomic
structure, and that low energy grain boundaries such ac
coincidence-site-lattice (CSL) boundaries have strong resistance to
intergranular corrosion. The concept of 'grain boundary design and control'
has been developed as grain boundary engineering (GBE). GBEed materials are
characterized by high frequencies of CSL boundaries which are resistant to
intergranular deterioration of materials, such as intergranular corrosion. A
thermomechanical treatment was tried to improve the resistance to the
sensitization by GBE. A type 304 austenitic stainless steel was cold-rolled
and solution-heat-treated, and then sensitization-heat-treated. The grain
boundary character distribution was examined by orientation imaging
microscopy (OIM). The intergranular corrosion resistance was evaluated by
electrochemical potentiokinetic reactivation (EPR) and ferric
sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was
reduced by the thermomechanical treatment and indicated a minimum at a small
roll-reduction. The frequency of CSL boundaries indicated a maximum at the
small reduction. The ferric sulfate-sulfuric acid test showed much smaller
corrosion rate in the thermomechanical-treated specimen than in the base
material. A high density of annealing twins were observed in the
thermomechanical-treated specimen. The results suggest that the
therrmomechanical treatment can introduce low energy segments in the grain
boundary network by annealing twins and can arrest the percolation of
intergranular corrosion from the surface. The effects of carbon content and
other minor elements on optimization in grain boundary character
distribution (GBCD) and thermomechanical parameters were also examined
during GBE.
174.
Kokawa, H., S. Karashima, et al. (1983). "Dissociation of Lattice
Dislocations in Coincidence Boundaries." Journal of Materials Science
18(4): 1183-1194.
175.
Komatsubara, M. and T. Imamura (2002). Observation of Secondary
Recrystallization Process in 3% Si-Steel with EBSD. ICOTOM 13, Seoul, Korea,
Trans Tech Publications Inc.
Secondary Recrystallization Process in 3% Si-Steel was observed with EBSD
technique in order to clarify the mechanism of unique growth of (110)[001]
grain. The process is composed with three stages, I, II, and III. The first
stage is the slight development of texture and grain size, and the second is
rapid growth of secondary grain. Both stages were found dominated by grain
boundary mobility characterized by neighbor grain orientations. Comparing
two types of models, High Energy Boundary and Coincidence Site Lattice, the
former could better explain the phenomena. At the second stage, grain growth
was dominated not only by grain boundary characterization, but also by the
size difference of neighbor grains. Therefore there were a lot of small
grains having completely different orientations from those of secondary
grains inside secondary grains after secondary recrystallization. At the
third stage, these small grains vanished during the higher temperature
annelaing. These results are well explained from the viewpoint of grain
boundary mobility and size difference of neighboring grain.
176.
Kono, S., T. Takano, et al. (2004). "Effect of bias treatment in the
CVD diamond growth on Ir(001)." Diamond and Related Materials
13(11-12): 2081-2087.
The effect of bias treatment (BT) on direct-current plasma CVD diamond
growth has been studied in situ by X-ray photoelectron diffraction (XPD)
together with LEED and XPS. It was found that C 1s XPD patterns from the
sample after BT are similar to those of diamond (001). Coverage of carbon
after BT is several tens of ML when BT is very successful. However, LEED
shows no diamond (001) spots for the sample after BT. These apparently
contradictory findings are explained by the sizes of the diamond (001)
crystallites, which, after BT, are large enough to produce C 1s XPD patterns
of diamond, but too small to have coherent interference spots in LEED. It is
concluded from this and other information that BT in a DC plasma creates
hetero-epitaxial diamond crystallites a few nm or less. These diamond
crystallites may be related to the atomically abrupt diamond/Ir interfaces
of DC plasma CVD-grown samples revealed by TEM [A. Sawabe, H. Fukuda, T.
Suzuki, Y. Ikuhara, T. Suzuki, Surf. Sci. 467 (2000) L845].
177.
Kononenko, O. V., V. N. Matveev, et al. (2000). "Electromigration
Activation Energy in Aluminum Conductors Tested by the Drift Velocity
Method." Scripta Materialia(42): 621-626.
178.
Kononenko, O. V., V. N. Matveev, et al. (2000). "Electromigration
Properties of Multigrain Aluminum Thin Film Conductors as Influenced by
Grain Boundary Structure." Journal of Materials Research.
179.
Konrad, J., S. Zaefferer, et al. (2004). Investigation of Nucleation
Mechanisms of Recrystallization in Warm Rolled Fe3Al Base Alloys. Second
Joint International Conference on Recrystallization and Grain Growth, ReX
& GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
It has been shown in literature that the mechanical properties of
Fe3Al base alloys are strongly dependent on the heat treatment
subsequent to warm rolling. Therefore, the recrystallization behavior of 3
different hot and warm rolled and annealed Fe3Al base alloys has
been investigated. Two of these alloys contain different forms and amounts
of second phase particles, while a pure binary alloy was taken as reference.
All alloys develop α-(<110>//RD) and
γ(<111>//ND) fiber bcc-type rolling and
annealing textures, however, the amount of α- and γ-fibers vary
in dependence of the alloy composition. The current work presents the
investigations on the nucleation process during annealing that has been
studied by means of high resolution backscatter electron diffraction (EBSD)
in the SEM. In particular, the occurrence of orientation gradients in the
deformed structure and their crystallographic relationship to the formation
of new grains was investigated. It was shown that small particles favor the
α-fiber component by hindrance of the growth of new grains. In
contrast, large particles lead to particle stimulated nucleation. This
weakens the overall texture but does not randomize it, since the orientation
gradients around particles keep a relationship with the matrix
orientation.
180.
Konrad, J., S. Zaefferer, et al. (2004). Thermomechanical Treatment of a
Fe3Al alloy. Integrity and Interdisciplinary Aspects of Intermetallics as
held at the 2004 MRS Fall Meeting, Boston, Massachusetts, USA, Materials
Research Society.
A binary Fe3Al alloy is investigated with respect to hot and warm
rolling behavior and microstructural as well as microtextural modifications.
Rolling has been performed in the A2 and B2 order regimes. The differences
in microstructure are investigated. The performed texture analysis reveals
the differences in hot and warm rolling textures depending on the hot
rolling temperature. On the basis of microtexture investigations by means of
electron backscatter diffraction (EBSD) differences concerning orientation
gradients and sub-grain structures are found. A model of combined
order-related and non-order related effects is proposed explaining the
observed material behavior. The results are used for process
modification.
181.
Konrad, J., S. Zaefferer, et al. (2005). "Hot deformation behavior of a
Fe3Al-binary alloy in the A2 and B2-order regimes."
Intermetallics 13(12): 1304-1312.
A binary Fe3Al alloy is investigated with respect to hot
deformation behavior and microstructural as well as microtextural
modifications. Applying the hot deformation simulator (WUMSI) to hot rolling
conditions in the A2 and B2-order regimes in combination with data analysis,
significant changes in deformation behavior are identified. These conditions
are selected for performing hot rolling experiments. The differences in
microstructure are investigated. On the basis of microtexture investigations
by means of electron backscatter diffraction (EBSD) differences concerning
orientation gradients and sub-grain structures are found. A model of
combined order-related and non-order related effects is proposed explaining
the observed material behavior. The information gained is the basis for the
optimization of the thermomechanical treatment to produce ductile
Fe3Al sheet material.
182.
Konrad, J., S. Zaefferer, et al. (2006). "Investigation of orientation
gradients around a hard Laves particle in a warm-rolled
Fe3Al-based alloy using a 3D EBSD-FIB technique." Acta
Materialia 54(5): 1369-1380.
We present a study of the microstructure around a hard Laves particle in a
warm-rolled intermetallic Fe3Al-based alloy. The experiments are
conducted using a system for three-dimensional orientation microscopy (3D
electron backscattering diffraction, EBSD). The approach is realized by a
combination of a focused ion beam (FIB) unit for serial sectioning with
high-resolution field emission scanning electron microscopy with EBSD. We
observe the formation of steep 3D orientation gradients in the
Fe3Al matrix around the rigid precipitate which entail in part
particle-stimulated nucleation events in the immediate vicinity of the
particle. The orientation gradients assume a characteristic pattern around
the particle in the transverse plane while revealing an elongated tubular
morphology in the rolling direction. However, they do not reveal a
characteristic common rotation axis. Recovered areas in the matrix appear
both in the transverse and rolling directions around the particle. The work
demonstrates that the new 3D EBSD-FIB technique provides a new level of
microstructure information that cannot be achieved by conventional 2D-EBSD
analysis.
183.
Kooi, B. J., R. J. Poppen, et al. (2003). "Ti3SiC2: A damage tolerant ceramic studied with
nanoindentations Acta Materialiaand transmission electron microscopy."
Acta Materialia 51: 2859-2872.
Nano-indentations into Ti3SiC2 grains with their basal
planes either oriented parallel or perpendicular with respect to the surface
were performed. These grains were selected on the basis of orientation
imaging microscopy (OIM). Scanning electron microscopy analysis of the
indentations clearly showed that for grains whose basal planes are oriented
parallel to the surface the elastic recovery and hardness values are lower,
the plastic deformation larger, and the pile up around the indents larger
than for the perpendicular orientation. These observations are explained by
the deformation mechanism, i.e. kink-band formation that operates at room
temperature in Ti3SiC2. Kink bands are more easily
formed during indentations when the basal planes are parallel to the
surface. For comparison indentations were also performed in 6H-SiC with the
basal planes parallel and perpendicular to the surface. For 6H-SiC the
results are identical for both orientations, apart from the initial peak
hardness and modulus that occur during loading for small indenter depths. In
both Ti3SiC2 and 6H-SiC these initial peak values for
both properties are lower when the basal planes are oriented perpendicular
or edge on to the surface. This is attributed to the cleavage fracture
between basal planes that occur under the indenter tip for the perpendicular
orientation initially during loading. Some results of the High Resolution
Transmission Electron Microscopy analysis of stacking faults in
Ti3SiC2 and Conventional TEM analysis of dislocation
walls in kink bands invoked during indentation are also shown. From the TEM
observations of wedge cracks, the shear and normal stresses that resulted in
these cracks are estimated and found to be in agreement with the estimates
derived from the nano-indentation experiments.
184.
Koops, U., D. Hesse, et al. (2002). "High-temperature oxidation of
CoGa: Influence of the crystallographic orientation on the oxidation
rate." Journal of Materials Research 17(No. 10):
2489-2498.
The crystallographic orientation plays an important role in high-temperature
oxidation of the intermetallic compound CoGa. When CoGa is exposed to air at
elevated temperatures, the oxide ß-Ga2O3 is
formed, and different scale growth rates are observed, depending on the
crystallographic orientation of the CoGa grains. This dependence is a
consequence of the anistropy of the gallium diffusion rate through the
ß-Ga2O3 scale and of a topotaxial orientation
relationship occurring between ß-Ga2O3 and CoGa.
The combination of ex situ techniques, such as transmission electron
microscopy and electron backscatter diffraction with optical microscopy,
applied in situ resulted in a thorough understanding of these realtions and
of the oxidation process in general.
185.
Kordic, S., R. A. M. Wolters, et al. (1993). "Correlation Between
Stress Voiding of Al(Si)(Cu) Metallizations and Crystal Orientation of
Aluminum Grains." Journal of Applied Physics 74(9):
5391-5394.
186.
Korhonen, T.-M. K., P. Turpeinen, et al. (2004). Mechanical properties of
near-eutectic Sn-Ag-Cu alloy over a wide range of temperatures and strain
rates. Lead-Free Solders and Processing Issues Relevant to Micro-Electronic
Packaging, Charlotte, North Carolina, USA, TMS; IEEE.
The deformation properties of near-eutectic Sn-Ag-Cu alloy were measured in
temperatures ranging from -25 to 125 degrees C, and down to strain rates of
about 10*10-9. Results have been combined into a stress versus
strain rate master curve. The measurements were done with dog-bone specimens
that have a 1-mm diameter, which corresponds to a typical solder joint
diameter in ball grid arrays (BGAs). Effects of cooling rate were also
studied, with cooling rates from 0.1 to 1 degrees/sec. The stress exponent
of the fast-cooled samples was high, about 16. The activation energy was
about 1 eV. The relatively high temperature dependence suggests that bulk
diffusion is dominating. Optical microscopy, scanning electron microscopy
(SEM) and electron backscattering diffraction (EBSD) were used to study the
microstructures of the test samples. The slower cooled samples had large
Ag3Sn plates, but the size of the plates was significantly reduced with the
faster cooling rates. The yield strength increased with cooling rate,
reflecting the larger amount of alloying elements remaining in the solution
and smaller, dispersed precipitates. For comparison, experiments were also
performed on binary AgSn and CuSn solders, pure Sn, and with two reduced
silver content SAC alloys, Sn-2.5% Ag-0.7% Cu and Sn-3.0%Ag-0.7%Cu.
187.
Korotayev, A. D. and Y. I. Pochivalov (1994). "Structure Mechanism of
Activated Recrystallization of Refractory-Metals." Fizika Metallov I
Metallovedenie 77(1): 131-141.
188.
Korsnes, T., H. Norum, et al. (2004). In-situ EBSD-analysis of abnormal
grain growth in friction stir welded 7075 T6 aluminium alloy. European
Microscopy Congress 2004, Antwerp, Belgium.
189.
Korte, C., J. K. Farrer, et al. (1999). On the Influence of Applied Fields
on Spinel Formation. MRS symposium.
190.
Kostrivas, A. D. and J. C. Lippold (2004). "Simulating Weld-Fusion
Boundary Microstructures in Aluminum Alloys." JOM 56(2):
65-72.
A fundamental study of weld-fusion soundary microstructural evolution in
aluminum alloys ws conducted in an effort to understand equiaxed grain zone
formation and fusion boundary nucleation and growth phenomena. In addition
to commercial aluminum alloys, experimental Mg-bearing alloys with Zr and Sc
additions were studied along with the widely used Cu- and Li- containing
alloy 2195-T8. This article describes work conducted to clarify the
interrelation among composition, base metal substrate, and temperature as
they relate to nucleation and growth phenomena at the fusion
boundary.
191.
Kotula, P. G. and C. B. Carter (1993). Solid-State Reactions Using Films
Deposited by Pulsed-Laser Ablation. 2nd International Conference on
Laser Ablation, Knoxville, T.N., American Institute of Physics
288.
Thin-film solid-state reactions may occur during growth of thin films by
pulsed-laser ablation or may intentionally be initiated in order to produce
buffer-layers or heterostructures. These reactions may also be used to
investigate phase transformations in general, in a well controlled manner
both from a kinetic and structural perspective. In this study, thin films of
nickel oxide (NiO) have been grown on single-crystal aluminum oxide (a-Al2O3) substrates by
pulsed-laser ablation and subsequently reacted to form the nickel-aluminate
spinel (NiAl2O4). The films of NiO were deposited
under various conditions of substrate temperature, laser fluence, and pulse
repetition rate in order to optimize the film quality. The films were
characterized by plan-view and cross-section scanning electron microscopy
(SEM) and transmission electron microscopy (TEM). In general, the films were
found to consist of two NiO twin orientations. Under the appropriate growth
conditions, these twins conformed to the original basal (0001)
α-Al2O3 substrate terraces. Reactions between
film and substrate were carried out at 1100°C in air. For intermediate
reaction times the reacted films contained smooth
interfacesbetween the NiAl2O4 and the
α-Al2O3 but irregular interfaces between the NiO
and the NiAl2O4. The roughness of the latter
interfaces could be directly attributed to twin boundaries, which were
present in the NiO film, acting as short-circuit diffusion paths for the
reactants.
192.
Krajewski, W. K. and A. L. Greer (2006). "EBSD study of ZnAl25 alloy
inoculated with ZnTi4 master alloy." Materials Science Forum
508: 281-285.
The microstructure of cast Zn-25 wt%Al alloy inoculated by addition of a
Zn-4 wt%Ti master alloy (ZnTi4) has been studied using scanning electron
microscopy and electron back-scatter diffraction (EBSD). It is found that
Ti(Al,Zn)3 particles act as nucleation centres for grains of the
primary solid solution of Zn in Al (alpha ' phase). The
Ti(Al,Zn)3 particles evolve in melt from the TiZn3
particles in the ZnTi4 master alloy. EBSD shows that alpha ' phase dendrites
are in the same crystallographic orientation as the Ti(Al,Zn)3
particles on which they nucleate. It is also found that some of the
Ti(Al,Zn)3 particles do not have any well-defined
crystallographic orientation relationship with the alpha ' phase. These
particles were probably pushed and then engulfed by growing alpha ' grains
which had already nucleated on other particles.
193.
Kral, M. V. (2005). "A crystallographic identification of intermetallic
phases in Al-Si alloys." Materials Letters 559(18):
2271-2276.
Iron-rich intermetallic phases are well known to be strongly influential on
mechanical properties in Al-Si alloys. Two important phases have been
previously designated as the relatively benign alpha -phase (with a `Chinese
Script' morphology) and the detrimental beta -phase (plate or
needle-shaped). While the common morphologies and effects of these phases
are generally agreed upon, there is some confusion in the literature
regarding the chemistry and/or crystallography of these phases. Using a
combination of scanning electron microscopy (SEM), energy dispersive X-ray
spectroscopy (EDS), electron backscatter diffraction pattern analysis
(EBSD), transmission electron microscopy (TEM) and convergent beam electron
diffraction (CBED), the present work showed that intermetallic phases in
cast eutectic Al-Si alloy intermetallics are often misidentified in the
current metallurgical literature. The alpha -phase particles were consistent
with cubic Al 19Fe 4MnSi 2 rather than
hexagonal. The phase often identified a beta -phase is actually consistent
with the tetragonal Al 3FeSi 2 (more correctly
designated as delta -phase) rather than monoclinic or orthorhombic.
194.
Kral, M. V. and G. Spanos (2003). "Crystallography of grain boundary
cementite dendrites." Acta Materialia 51(2): 301-311.
The crystallography and morphology of proeutectoid grain boundary cementite
precipitates were studied in an isothermally transformed Fe-1.3%C-12%Mn
steel. Grain boundary cementite precipitates develop with complex variations
of a morphology that can be described as fern-like dendrites growing
preferentially within and along austenite grain boundaries. The dendritic
morphology was made most readily apparent by deep etching specimens of the
alloy whose growth had been arrested after relatively short times during the
solid state austenite->cementite transformation. Trace analysis revealed
that these precipitates usually have no crystallographically preferred
primary or secondary dendrite arm growth directions. Electron Backscattered
Diffraction pattern analysis showed that most of the grain boundary
cementite precipitates approximated one of the known cementite-austenite
crystallographic orientation relationships (OR) with at least one of its
adjacent austenite grains. Occasionally, the grain boundary cementite
exhibited an OR that achieved `best fit' directions between the cementite
and austenite in both adjacent austenite grains.
195.
Kral, M. V., H. R. McIntyre, et al. (2004). "Identification of
intermetallic phases in a eutectic Al-Si casting alloy using electron
backscatter diffraction pattern analysis." Scripta Materialia
51(3): 215-219.
Intermetallic phases in sand cast eutectic Al-Si alloys were characterized
using a combination of SEM, EDS and EBSD pattern analysis. Chinese script
α-phase particles were consistent with cubic
Al19(Fe,Mn)5Si2. Plate-shaped β-phase
particles were consistent with tetragonal
Al3(Fe,Mn)Si2. Copyright 2004 Acta Materialia Inc.
Published by Elsevier Ltd. All rights reserved.
196.
Krenn, C. R., J. W. Morris Jr., et al. (1997). The Crystallography of
Fatigue Crack Initiation in Two Austenitic Fe-Ni Superalloys. High Cycle
Fatigue of Structural Materials. W. O. Soboyejo and T. S. Srivatsan.
Warrendale, Pennsylvannia, The Minerals, Metals & Materials Society:
327-337.
197.
Krieger Lassen, N. C. (1994). Automated Determination of Crystal
Orientations from Electron Backscattering Patterns, Danmarks Tekniske
Universitet.
198.
Krieger Lassen, N. C. (1996). "Automatic localisation of electron
backscattering pattern bands from Hough transform." Materials Science
and Technology 12(10): 837-843.
Current methods of data representation for electron backscatter diffraction
(EBSD) measurements are reviewed. Obtaining diffraction data from
microstructures using EBSD has become a relatively straightforward
procedure, and EBSD software packages are used to represent these data as
qualitative statistics in the form of ideal orientations, pole figures,
inverse pole figures. Euler space, and Rodrigues-Frank space. Quantitative
statistics in the form of secondary computation allows full microtextural
analysis. Additionally, the power of EBSD is demonstrated through positional
information representation Through experimental examples, the conversion of
EBSD data to statistical information to facilitate interpretation of results
is demonstrated. (20 References).
199.
Krieger Lassen, N. C. (1996). "The relative precision of crystal
orientations measured from electron backscattering patterns." Journal
of Microscopy 181(1): 72-81.
Recently developed statistical methods for analysing orientation data are
presented and applied here in a study of the precision by which crystal
orientations can be measured from electron backscattering patterns. The use
of these methods allows a direct comparison to be made between the precision
obtained with manually and automatically localized bands, which is important
owing to a more and more widespread use of fuly automatic analysis of
electron backscattering patterns. Curves which show how the precision
depends on the pattern quality and on the number of bands used for the
orientation measurements are presented for both manually and automatically
localized bands. Typical values for the relative precision of crystal
orientations measured from electron backscattering patterns are shown to be
of the order of 0&bul;5° for manually localized bands and 0&bul;75°
for automatically localized bands, when about ten bands are used for the
measurements. In a more realistic situation, where a careful operator is
willing to localize four to five bands in each pattern, the precision of the
measured crystal orientations is similar to theat obtained for automatically
localized bands.
200.
Krieger Lassen, N. C. (1998). "Automatic high-precision measurements of
the location and width of Kikuchi bands in electron backscatter diffraction
patterns." Journal of Microscopy 190(3): 375-391.
The demands for reliability and precision of crystal orientation data
obtained through automatic analysis of electron backscattering patterns
(EBSPs) in the SEM result in similar demands on the quality of the band
position data which is provided by an image analysis procedure. This paper
describes a new image processing procedure which is capable of providing
accurate measurements of the location and width of typically 10-15 bands in
digitized EBSPs of average quality. The new procedure is based on the Hough
transform (HT) for line detection, and employs a special backmapping
technique for generating two simplified HTs which separately focus on bright
and dark lines in the images. A coordinated search for peaks in the two HTs
leads to precise estimates of both the position and the width of bands in
the patterns. A visual evaluation of the data produced by the new procedure
shows that it performs significantly better than the conventional procedure
with regard to both reliability and precision. Additionally, the measured
band width data are fairly precise and can be used for obtaining a more
robust and reliable indexing of the bands. Finally, the computational costs
of the new procedure are smaller than for the conventional
procedure.
201.
Krieger Lassen, N. C. (1998). "New procedure for automatic high
precision measurements of the position and width of bands in backscatter
Kikuchi patterns." Materials Science Forum 273-275:
201-208.
A high reliability and precision of crystal orientation data obtained
through automatic analysis of backscatter Kikuchi patterns (BKP) from the
SEM require a high quality of the band position data which is provided by an
image analysis procedure. This paper presents a new pattern recognition
procedure which is capable of providing accurate measurements of the
location and width of 10 to 15 bands in BKPs of average quality. The
procedure is based on the Hough transform (HT) for line detection, and
applies a special backmapping technique for generating two simplified HTs
which separately focus on bright and dark lines in the patterns. A
coordinated search for peaks in the two HTs leads to precise measurements of
both the position and width of bands in the patterns. The performance of the
new procedure was tested on 100 patterns of varying quality obtained from a
sample of partly recrystallized copper. A quantitative comparison of the new
procedure with the traditional HT-based procedure shows that the former
provides significantly more reliable and precise band position measurements.
Furthermore, the computational costs of the new procedure are about 20
percent smaller than for the traditional procedure. (Author abstract)
[References: 13]
202.
Krieger Lassen, N. C. (1999). "Source point calibration from an
arbitrary electron backscattering pattern." Journal of Microscopy
195(3): 204-211.
Precise knowledge of the position of the source point is a requirement if
electron backscattering patterns (EBSPs) are to be used for crystal
orientation measurements or other types of measurements which demand a
geometrical analysis of the patterns. Today, possibly the most popular
method for locating the source point is a computational technique which uses
the positions of a number of indexed Kikuchi bands for calculating the
coordinates of the point. A serious limitation of this calibration technique
is, however, that the localized bands must first be indexed, which is
difficult if the location of the source point is not known with reasonable
precision.
This paper describes a new technique which determines the location of the
source point from the positions of a number of bands in an arbitrary EBSP.
Besides the positions of the Kikuchi bands, the only information which is
required by this new calibration procedure is the same crystallographic
information which is used for normal indexing of EBSPs. The procedure is
shown to work successfully with patterns from a simple cubic crystal, as
well as with patterns from an orthorhombic BiSCCO superconductor. In the
former case, four bands are shown to be sufficient to ensure a unique
determination of the source point, whereas five bands are required in the
latter case. Once the bands have been localized, the time required for
calculating the source point position is of the order of 1 min on a standard
PC.
203.
Krieger Lassen, N. C. and D. Juul Jensen (1999). Automatic Recognition of
Recrystallized Grains in Partly Recrystallized Samples from Crystal
Orientation Maps. The Twelfth International Conference on Textures of
Materials (ICOTOM 12), McGill University, Montreal, Canada, Ottawa, NRC
Research Press.
204.
Krieger Lassen, N. C. and J. B. Bilde–SØrensen (1993). "Calibration of an Electron Backscattering Pattern Set-up."
Journal of Microscopy - Oxford 170(MAY): 125-129.
205.
Krieger Lassen, N. C., D. Juul Jensen, et al. (1994). "Automatic
recognition of deformed and recrystallized regions in partly recrystallized
samples using electron backscattering patterns." Materials Science
Forum 157-162: 149-158.
206.
Krieger Lassen, N. C., D. Juul Jensen, et al. (1994). "On the
Statistical Analysis of Orientation Data." Acta Crystallographica A
50: 741-748.
207.
Krieger Lassen, N. C., K. Conradsen, et al. (1992). "Image-processing
procedures for analysis of electron back scattering patterns." Scanning
Microscopy 6(1): 115-121.
The authors report the use of electron backscatter diffraction (EBSD) to
elucidate more precisely the orientation characteristics of carbides in both
the hypereutectic and hypoeutectic alloy specimens. The result confirmed
previously obtained have X-ray data which indicated a monocrystalline
orientation of carbide rods within a grain in the hypereutectic alloy
specimen and random orientation of carbide rods in the hypoeutectic
specimen. A detailed study was also made of the mechanism of carbide growth.
(7 References).
208.
Kruger, S. E., G. Lamouche, et al. (2004). Laser Ultrasonic Monitoring of
Recrystallization of Steels. Materials Science & Technology 2004, New
Orleans, Louisiana, USA, The Association for Iron and Steel Technology
(AIST) and TMS (The Minerals, Metals and Materials Society).
Laser-ultrasonics is a non-destructive and non-contact technique that allows
ultrasonic assessment of some materials characteristics, like grain size,
phase fraction and texture. The suitability of this technique has already
been demonstrated in metals processing environments. In this paper,
ultrasonic velocity and absorption are measured during annealing of low
carbon and IF steels. Velocity variations due to changes in texture during
recrystallization are sensitive to recrystallization stages as confirmed by
metallographic and texture measurements. The absorption (or internal
friction) of ultrasonic waves is also shown to be sensitive to annealing.
The absorption increases during annealing in steels due to an increase of
the magnetoelastic damping. The potential of using parameters such as
velocity and absorption for real-time monitoring of annealing in production
lines is discussed.
209.
Krupp, U. T., V.B.; Wagenhuber, E.-G. (2005). The role of
oxygen-grain-boundary diffusion during intercrystalline oxidation and
intergranular fatigue crack propagation in alloy 718. 6th International
Symposium on Superalloys 718, 625, 706 and Derivatives, Pittsburgh,
Pennsylvania, USA.
The design of new high-efficient gas turbines is closely associated with the
need to increase the service temperature of its components. Today, the
applicability of the polycrystalline Ni-base superalloy 718 is limited by
its susceptibility to fast intergranular cracking during low-cycle fatigue
in combination with hold times at maximum tensile stress and high
temperatures, typically of about 650eatment w C. Static four-point-bending
tests and fatigue tests with and without hold times on cylindrical specimens
in a temperature range of 650 was subje C and in various atmospheres have
revealed that this kind of intergranular cracking is not due to the
formation of massive oxidation products along the grain boundaries. It can
rather be attributed to the mechanism of "dynamic embrittlement"
at a nanoscale, i.e., diffusion of elemental oxygen into highly stressed
grain boundaries ahead of a growing crack, followed by decohesion. By
microstructural evaluation of the mechanical tests and thermogravimetric
oxidation experiments using analytical scanning electron microscopy (SEM) in
combination with automated electron back-scatter diffraction (EBSD), it
became evident that only a part of the grain boundaries is prone to
oxygen-induced attack. This observation gave rise to applying a
grain-boundary-engineering-type treatment to the as-received alloy 718
material, resulting in an increase in the fraction of low-$Σ CSL grain
boundaries (coincidence site lattice). These special boundaries seem to have
a high resistance to oxygen grain boundary diffusion, resulting in a
decrease in the crack-propagation rate at the lower temperature of 650ially
in C and a less-pronounced intercrystalline oxidation attack at higher
temperatures.
210.
Krupp, U., O. Duber, et al. (2004). "Application of the EBSD technique
to describe the initiation and growth behaviour of microstructurally short
fatigue cracks in a duplex steel." Journal of Microscopy 213(Pt
3): 313-320.
Up to 90% of the fatigue life of engineering alloys results from the
initiation and propagation of microstructurally short cracks. Owing to their
strong interactions with microstructural features, e.g. grain and phase
boundaries, they exhibit substantially non-uniform propagation kinetics as
compared with the growth rate of long cracks, which can be well described
using a power-law function of the range of the stress-intensity factor
DeltaK. In the present paper interactions between the crystallographic
misorientation of grain and phase boundaries and microcracks in an
austenitic/ferritic stainless steel are discussed and quantified by means of
fatigue experiments in combination with the electron backscattered
diffraction technique. In the second part a numerical model for the
simulation of microcracks is introduced, which is capable of taking real
microstructural arrangements into consideration.
211.
Krupp, U., W. Floer, et al. (2002). "Mechanisms of short-fatigue-crack
initiation and propagation in a beta -Ti alloy." Philosophical Magazine
A 82(17-18): 3321-3332.
The microstructurally short-crack initiation and early propagation were
studied on the metastable beta -Ti alloy Timetal LCB in the solution
heat-treated bcc beta microstructure under symmetrical pull-push fatigue
testing. By means of a finite-element treatment in combination with local
displacement measurements applying a laser interferometric
strain-displacement gauge (ISDG), it was shown that elastic anisotropy gives
rise to high mechanical stresses at certain grain boundaries (GBs).
Large-angle GBs were observed to be preferred sites for short-crack
initiation. Two modes of fatigue crack initiation were found: one is crack
formation along slip bands, often resulting in transgranular crack
propagation; the second is intergranular cracking of GBs. Using electron
back-scattered diffraction (EBSD), local crystallographic orientations were
determined and hence the role of GB types in the process of short crack
initiation and growth could be taken into account. On the basis of the
experimental observations and measurements, the preferred crystallographic
conditions for short crack initiation and growth were revealed. The ISDG
system was applied to measure the local crack opening displacements of short
cracks in order to characterize the dependence of the short-crack closure
phenomena on the applied load.
212.
Kudou, T., T. Onishi, et al. (2005). "Microstructural analysis of
Y2O3-stabilized zirconia by EBSP (electron backscatter
diffraction pattern)." R and D: Research and Development Kobe Steel
Engineering Reports 55(1): 56-59.
The EBSP technique was applied to the microstructural analysis of 3mol%
Y2O3-stabilized zirconia which has a very fine
microstructure. It was found that the phase identification of monoclinic and
cubic zirconia was possible with this technique. However, it was difficult
to distinguish tetragonal zirconia from cubic zirconia with a high
confidence. The results also showed that the EBSP technique is useful for
the evaluation of various microstructural characteristics such as grain
size, morphology or crystal orientation.
213.
Kulka, M., A. Pertek, et al. (2006). "The influence of carbon content
in the borided Fe-alloys on the microstructure of iron borides."
Materials Characterization 56(3): 232-240.
This paper presents the results of Electron Back-Scatter Diffraction (EBSD)
analyses of the borided layers produced on substrate of varying carbon
content. Two types of materials were investigated: borided Armco iron of
very low carbon content and borocarburized chromium- and nickel-based steels
of high carbon content beneath iron borides. The tetragonal phase
Fe2B was identified in all materials studied. It was difficult to
obtain an EBSD pattern from iron boride (FeB) because of its presence at low
depths below the surface, and because of the rounded corners of the
specimens. EBSD provided information on the orientation of Fe2B
crystals. In case of the low-carbon Armco iron the crystallographic
orientation was constant along the full length of the Fe2B
needle. The EBSPs obtained from borocarburized steel indicate that the
crystallographic orientation of the Fe2B phase changes along the
length of the needle. This is the result of hindered boron diffusion due to
boriding of the carburized substrate. The increased resistance to friction
wear of borocarburized layers arises from two reasons. One is the decreased
microhardness gradient between the iron borides and the substrate, which
causes a decrease in the brittleness of the iron borides and an improved
distribution of internal stresses in the diffusion layer. The second is the
changeable crystallographic orientation of iron borides, which leads to the
lower texture and porosity of borided layers. These advantageous properties
of the borocarburized layer can be obtained if the carbon content beneath
the iron borides is no more than about 1.0-1.2 wt.% C.
214.
Kumar, M. and B. W. Reed (2004). Stereological corrections for grain
boundary number fractions in three dimensions. Interfacial Engineering for
Optical Properties III, San Francisco, California, USA, MRS.
Two-dimensional (2D) cross sections through three-dimensional (3D)
polycrystalline materials present a biased picture of the statistical
properties of grain boundary networks. These properties are essential to
many practical applications such as grain boundary engineering. We show a
simple correction that will partly correct for the sampling biases by
removing the effect of the correlation between grain boundary type and grain
boundary area. This correction alters number fraction estimates by as much
as similar to 60% for Σ3 boundaries in the highly-twinned copper
samples we consider. We also estimate the bias introduced by the correlation
between boundary type and boundary shape, which for many materials
represents perhaps a 10% shift in the measured statistics, so that the
simple method we propose should correct for the majority of the bias in
favorable cases. This document was prepared as an account of work sponsored
by an agency of the United States Government. Neither the United States
Government nor the University of California nor any of their employees,
makes any warranty, express or implied, or assumes any legal liability or
responsibility for the accuracy, completeness, or usefulness of any
information, apparatus, product, or process disclosed, or represents that
its use would not infringe privately owned rights. Reference herein to any
specific commercial product, process, or service by trade name, trademark,
manufacturer, or otherwise, does not necessarily constitute or imply its
endorsement, recommendation, or favoring by the United States Government or
the University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.
215.
Kumar, M., A. J. Schwartz, et al. (1999). Modifications in the grain
boundary character distribution in FCC materials through thermomechanical
processing. Twelfth International Conference on Textures of Materials
(ICOTOM 12), McGill University, Montreal, Canada, NRC Research
Press.
216.
Kumar, M., A. J. Schwartz, et al. (2001). "Correlating obsevations of
deformation microstructures by TEM and automated EBSD techniques."
Materials Science and Engineering A 309-310: 78-81.
The evolution of the deformed microstructure as a function of imposed
plastic strain is of interest as it provides information on the material
hardening characteristics and mechanism(s) by which cold work energy is
stored. This has been extensively studied using transmission electron
microscopy (TEM), where the high spatial and orientational resolution of the
technique is used in advantage to study local phenomenon, such as
dislocation core structures and interactions of dislocations. With the
recent emergence of scanning electron microscope (SEM)- based automated
electron backscatter diffraction (EBSD) techniques, it has now become
possible to make mesoscale observations that are statistical in nature and
complement the detailed TEM observations. Correlations of such observations
will be demonstrated for the case of Ni-base alloys, which are typically
non-cell forming solid solution alloys when deformed at ambient
temperatures. For instance, planar slip is dominant at low-strain levels but
evolves into a microstructure where distinct crystallographic
dislocation-rich walls form as a function of strain and grain orientation.
Observations recorded using both TEM and EBSD techniques are presented and
analyzed for their implication on subsequent annealing
characteristics.
217.
Kumar, M., A. J. Schwartz, et al. (2002). "Microstructural evolution
during grain boundary engineering of low to medium stacking fault energy fcc
materials." Acta Materialia 50(10): 2599-2612.
Grain boundary engineering comprises processes by which the relative
fractions of so-called special and random grain boundaries in
microstructures are manipulated with the objective of improving materials
properties such as corrosion, creep resistance, and weldability. One such
process also referred to as sequential thermomechanical processing (TMP),
consists of moderate strains followed by annealing at relatively high
temperatures for short periods of time. These thermomechanical treatments on
fcc metals and alloys with low to medium stacking fault energies result in
microstructures with high fractions of Σ3n and other special
boundaries, as defined by the coincidence site lattice (CSL) model. More
importantly, the interconnected networks of random boundaries are
significantly modified as a consequence of the processing. The modifications
in the grain boundary network have been correlated with post-mortem electron
backscatter diffraction (EBSD) and transmission electron microscopy (TEM)
observations of the deformed and annealed states of the material. The
evolution of the microstructure to a high fraction of Σ3n
boundaries is correlated with the decomposition or dissociation of immobile
boundaries during annealing. This is evidenced by TEM observations of the
decomposition of relatively immobile boundaries into two components, one
with very low energy and thus immobile, and the other a highly mobile
boundary that migrates into neighboring areas of higher strain levels. The
formation of low-energy grain boundaries through this mechanism and its
effect on boundary network topology is discussed within the context of grain
boundary engineering and linked to known microstructural evolution
mechanisms.
218.
Kumar, M., C. A. Schuh, et al. (2003). Connectivity in random grain boundary
networks. Electron Microscopy: Its Role in Materials Science. Mike Meshii
Symposium. Proceedings of a Symposia, San Diego, CA, USA, TMS - Miner.
Metals & Mater. Soc.
Mechanical properties of FCC metals and alloys can be improved by exercising
control over the population of grain boundary types in the microstructure.
The existing studies also suggest that such properties tend to have
percolative mechanisms that depend on the topology of the grain boundary
network. With the emergence of SEM-based automated electron backscatter
diffraction (EBSD), statistically significant datasets of interface
crystallography can be analyzed in a routine manner, giving new insight into
the topology and percolative properties of grain boundary networks. In this
work, we review advanced analysis techniques for EBSD datasets to quantify
microstructures in terms of grain boundary character and triple junction
distributions, as well as detailed percolation-theory based cluster
analysis.
219.
Kumar, V., Z. Z. Fang, et al. (2006). "An analysis of grain boundaries
and grain growth in cemented tungsten carbide using orientation imaging
microscopy." Metallurgical and Materials Transactions A 37(3):
599-607.
Tungsten carbide grains are usually prism-shaped triangular platelets in
cemented tungsten carbide materials, owing to the highly anisotropic nature
of tungsten carbide grains. The misorientation distribution function (MODF)
shows a preferred misorientation relationship between WC/ WC crystals. The
misorientation relationship is characterized as 90 deg misorientation about
the [1010] axis. The carbide-carbide boundaries with 90 deg rotation about
the [1010] axis are low-energy boundaries and play an important role in
grain growth and densification during sintering. In this study, the
evolution of carbide-carbide boundaries with 90 deg rotation about the
[1010] axis during the sintering process is determined quantitatively using
orientation imaging microscopy (OIM). The evolution of boundaries is
correlated with grain growth. The rapid grain growth at early stages of
sintering is attributed to coalescence of grains along the 90 deg low-energy
boundaries. The origin of these boundaries and their role in grain growth
during sintering are also discussed.
220.
Kunikova, T., H. Wendrock, et al. (2004). "EBSD investigation of
intergranular corrosion attack on low interstitial stainless steel."
Materials and Corrosion 55(6): 437-443.
Grain boundary effect on corrosion behaviour of low interstitial AISI 316LN
austenitic stainless steel after homogenization and heat treatment at 700
and 800 results C was investigated by means of Electron Backscattered
Diffraction (EBSD) technique. Rapid oxalic acid etch test (ASTM A262-
practice A) was used to determine steel susceptibility to intergranular
corrosion. An attempt to quantify oxalic acid etch test results was also
made. Beneficial effect of low carbon and nitrogen content on grain boundary
precipitation and corrosion was observed. No changes neither in grain
orientations nor in grain boundary types between sensitised and
non-sensitised steel states using orientation measurements were recorded.
Twin boundaries were found in all samples with highest amount and only small
occurrence changes. CSL categorizations showed only little increase of
special boundary fractions with increasing time and temperature of heat
treatment. Irrespective to annealing conditions a continued network of
random boundaries was retained. Additionally, based on misorientation
measurement of 50 grooved grain boundaries, a tendency for preferred attack
of high angle boundaries (30-55train in) was noted.
221.
Kunze, K., S. I. Wright, et al. (1993). "Advances in Automatic EBSP
Single Orientation Measurements." Textures and Microstructures
20(1-4): 41-54.
222.
Kuprat, A., D. George, et al. (2003). "Modeling microstructure
evolution in three dimensions with Grain3D and LaGriT." Computational
Materials Science 28: 199-208.
This paper will describe modeling microstructure evolution using a
combination of our gradient-weighted moving finite elements code, Grain3D
and our 3-D unstructured grid generation and optimization code, LaGriT.
Grain boundaries evolve by mean curvature motion, and Grain3D allows for the
incorporation of grain boundary orientation dependence modeled as
anisotropic mobility and energy. We also describe the process of generating
an initial computational grid from images obtained from electron backscatter
diffraction. We present the grid optimization operations developed to
respond to changes in the physical topology such as the collapse of grains
and to maintain uniform computational grid quality. For 3-D columnar
microstructures, validation of the method is demonstrated by comparison with
experiments. For large systems of fully 3-D microstructures, simulations
compare favorably to the parabolic law of normal grain growth.
223.
Kuramae, H., K. Okada, et al. (2005). Parallel Computing of Multi-scale
Finite Element Sheet Forming Analyses Based on Crystallographic
Homogenization Method. NUMISHEET 2005: 6th International Conference and
Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes,
Detroit, Michigan, USA, American Institute of Physics.
Since the multi-scale finite element analysis (FEA) requires large
computation time, development of the parallel computing technique for the
multi-scale analysis is inevitable. A parallel elastic/crystalline
viscoplastic FEA code based on a crystallographic homogenization method has
been developed using PC cluster. The homogenization scheme is introduced to
compute macro-continuum plastic deformations and material properties by
considering a polycrystal texture. Since the dynamic explicit method is
applied to this method, the analysis using micro crystal structures computes
the homogenized stresses in parallel based on domain partitioning of
macro-continuum without solving simultaneous linear equations. The
micro-structure is defined by the Scanning Electron Microscope (SEM) and the
Electron Back Scan Diffraction (EBSD) measurement based crystal
orientations. In order to improve parallel performance of elastoplasticity
analysis, which dynamically and partially increases computational costs
during the analysis, a dynamic workload balancing technique is introduced to
the parallel analysis. The technique, which is an automatic task
distribution method, is realized by adaptation of subdomain size for
macro-continuum to maintain the computational load balancing among cluster
nodes. The analysis code is applied to estimate the polycrystalline sheet
metal formability.
224.
Kuramoto, S., T. Furuta, et al. (2005). "EBSP Analysis on
Microstructure of Gum Metal after Plastic Deformation." Journal of the
Japan Institute of Metals 69(11): 953-961.
EBSP (electron backscattering pattern) analysis was performed on
microstructure of three beta titanium alloy specimens after cold working to
study peculiar plastic behavior of the multifunctional alloy, gum metal. The
specimens employed were Ti-36% Nb-2%Ta-3%Zr-0.3%O (mass%) alloy (gum metal)
and two reference alloys having lower and higher bcc phase stability than
that of gum metal. Deformation twinning of {332} <113> was observed in
the specimen with lower bcc stability, and dislocation glide in the specimen
with higher bcc stability. Orientation boundaries with rotation angle of
10-30 degrees were observed in gum metal specimen, and they are considered
to be identical to the giant planar faults which were observed in TEM in the
previous study. It seems that the giant faults act as grain boundaries and
numerous subgrains are generated in the later stage of plastic deformation.
Amount of crystallographic rotation in deformed gum metal specimens was very
large, which implies that huge elastic energy was stored during plastic
deformation.
225.
Kuramoto, S., T. Furuta, et al. (2006). "Plastic Deformation in a
Multifunctional Ti-Nb-Ta-Zr-O Alloy." Metallurgical and Materials
Transactions A 37(3): 657-662.
Mechanisms for plastic deformation in the newly developed Ti-24 at. pct (Ta
+ Nb + V)-(Zr,Hf)-O alloys (Gum Metal) were investigated in relation to
their unique properties. Transmission electron microscopy revealed that the
microstructure after deformation was characterized by highly distorted
crystal images, which are accompanied by numerous "giant faults."
Such plastic behavior implies that a large amount of elastic stain energy
was stored discretely and hierarchically during cold working. Calculated
elastic constants of the Ti-X (Nb,Ta,Mo,V) binary systems predicted that
Young's modulus in <001> and shear moduli along some directions
including slip systems in a bcc crystal were extraordinary small. The low
modulus not only well explains the highly distorted microstructure observed
in the cold-worked specimens, but also signifies that ideal shear strength
of the developed alloys is a very small value, which is close to the
practical strength required for plastic deformation in the alloy. This
implies that the giant faults observed in the deformed specimen were formed
without the aid of dislocation glide.
226.
Kurban, M., U. Erb, et al. (2006). "A grain boundary characterization
study of boron segregation and carbide precipitation in alloy 304 austenitic
stainless steel." Scripta Materialia 54(6): 1053-1058.
Higher frequencies of low Σ boundaries, satisfying the
Palumbo–Aust criterion, resulted in greater resistance to boron
segregation and carbide formation at grain boundaries in alloy 304. Also,
boron desegregated from grain boundaries and became incorporated into
isolated grain boundary carbides, thereby providing a discontinuous path for
impurity segregation.
227.
Kurzydlowski, K. J., J. Wyrzykowski, et al. (1986). "Extrinsic
Grain-Boundary Dislocation Spreading Temperature in Copper." Materials
Science and Technology 2(4): 420-421.
228.
Kusnierz, J., M.-H. Mathon, et al. (2005). Texture of Al-Cu alloys deformed
by ECAP. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech
Publications.
Materials of ultra-fine grained microstructure (submicrometer grain size)
exhibit large strength, hardness and ductility and also the increased
toughness in comparison with conventional coarse-grained ones. In these
materials also the super-plastic flow at lower temperatures is observed.
This behaviour may be interesting when aluminium alloys like AlCuZr, used in
superplastic forming, are considered. In the paper, the methods of preparing
such materials by equal-channel angular pressing (ECAP) is proposed and the
texture analysis, based on neutron diffraction pole figure measurements and
calculated orientation distribution function of two alloys AlCu4SiMn and
AlCu5AgMgZr is discussed. The influence of short time recrystallization is
discussed in relation with TEM and SEM observations.
229.
Kusnierz, J., M.-H. Mathon, et al. (2005). "Microstructure and Texture
of ECAP Processed AlCu4SiMn and AlCu5AgMgZr
Alloys." Archives of Metallurgy and Materials 50(2):
367-377.
The superplastic flow occurring in materials of ultra-fine grained structure
allows to reducing the drawing temperature. It may be profitable when
applied to aluminium alloys like AlCuZr, subjected to superplastic forming.
The texture, based on neutron diffraction pole figure measurements of two
alloys i.e. AlCu4SiMn and AlCu5AgMgZr during the
equal-channel angular pressing (ECAP) is discussed in the paper. Structure
observations by means of optical microscopy, transmission electron
microscopy (TEM) and electron back scattered diffraction (EBSD) technique
for OIM(TM) and local texture measurements have been applied to obtain a
precise and detailed description of structure and orientation
changes.
230.
Kutsukake, K., N. Usami, et al. (2004). "Fabrication of
SiGe-on-insulator by rapid thermal annealing of Ge on Si-on-insulator
substrate." Applied Surface Science 224(1-4): 95-98.
We report on fabrication of SiGe single crystal film on insulator by a
simple approach including a growth of a thin Ge film on a commercially
available SOI substrate, formation of a SiO2 protective layer,
and rapid thermal annealing (RTA) in an Ar atmosphere. Homogeneity of the
local Si fraction in SiGe-on- insulator (SGOI) was found to be closely
connected with the SiGe phase diagram, and RTA below the solidus line is
required to obtain homogeneous SGOI. In spite of the high annealing
temperature beyond the melting point of Ge, obtained SGOI was revealed to be
single crystalline as evidenced by electron back scattering pattern
analysis.
231.
Kuwano, N., K. Horibuchi, et al. (2002). "Electron microscopy analyses
of microstructures in ELO-GaN." Journal of Crystal Growth
237-239: 1047-1054.
Several topical results of electron microscope analyses for microstructures
in epitaxial lateral overgrown (ELO)-GaN are reported. (1) Dislocations
lying on (0 0 0 1), or horizontal dislocations (HDs), are generated in
ELO-GaN layers overlying on a mask of a-SiO2. The HDs have a
shape of loop or semi- loop, and the morphology suggests that the HDs are
generated through a multiplication mechanism with the assistance of internal
stress. (2) On GaInN/GaN, a pit is formed at the end of a threading
dislocation (TD) of any Burgers vector, a, c or a+c. The density and
distribution of TDs in ELO-GaN can be estimated by observing these growth
pits after a subsequent deposition of a thin GaInN layer on the ELO-GaN. The
critical thickness for the formation of pits has a dependency upon the
concentration of In in GaInN and the Burgers vector. (3) It was demonstrated
that electron backscattering diffraction pattern (EBSP) analyses can
estimate a two-dimensional distribution of c-axis orientation of ELO-GaN for
a wide area with an accuracy of 0.2° or better.
232.
Kwakman, L. F. T., N. Bicais-Lepinay, et al. (2005). The role of a physical
analysis laboratory in a 300 mm IC development and manufacturing centre.
Characterization and Metrology for ULSI Technology 2005, Richaredson, Texas,
USA.
To remain competitive IC manufacturers have to accelerate the development of
most advanced (CMOS) technology and to deliver high yielding products with
best cycle times and at a competitive pricing. With the increase of
technology complexity, also the need for physical characterization support
increases, however many of the existing techniques are no longer adequate to
effectively support the 65-45 nm technology node developments. New and
improved techniques are definitely needed to better characterize the often
marginal processes, but these should not significantly impact fabrication
costs or cycle time. Hence, characterization and metrology challenges in
state-of-the-art IC manufacturing are both of technical and economical
nature. TEM microscopy is needed for high quality, high volume analytical
support but several physical and practical hurdles have to be taken. The
success rate of FIB-SEM based failure analysis drops as defects often are
too small to be detected and fault isolation becomes more difficult in the
nano-scale device structures. To remain effective and efficient, SEM and
OBIRCH techniques have to be improved or complemented with other more
effective methods. Chemical analysis of novel materials and critical
interfaces requires improvements in the field, for example, SIMS, ToF-SIMS.
Techniques that previously were only used sporadically, like EBSD and XRD,
have become a `must' to properly support backend process development. At the
bright side, thanks to major technical advances, techniques that previously
were practiced at laboratory level only now can be used effectively for
at-line fab metrology: Voltage Contrast based defectivity control, XPS based
gate dielectric metrology and XRD based control of copper metallization
processes are practical examples. In this paper capabilities and
shortcomings of several techniques and corresponding equipment are presented
with practical illustrations of use in our Crolles facilities.
233.
Kwon, D., C. Lee, et al. (2005). "Electromigration resistance-related
microstructural change with rapid thermal annealing of electroplated copper
films." Thin Solid Films 475(No 1-2, Special Edition):
58-62.
Electromigration is now a primary concern regarding reliability of
ultralarge scale integrated circuits (ULSI) because of increasing current
density in miniatured devices. Effects of rapid thermal annealing (RTA)
treatment on the microstructural parameters on the electromigration
resistance of electroplated Cu films were determined using scanning electron
microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD)
analysis techniques. Also electron backscattered diffraction (EBSD) patterns
were used to characterize the texture of the Cu thin films. It has been
found that the electromigration resistance of the electroplated Cu film is
enhanced with increasing the annealing temperature in the temperature range
from 200 to 500 degrees C. Nitrogen is more favorable than vacuum as RTA
atmosphere since nitrogen atmosphere offers lower resistivity and smoother
film surface. Also the dependence of the bamboo structure on the annealing
temperature and the line width of the Cu interconnect is discussed. If the
line width is a quarter micron, a bamboo structure will be obtained by the
RTA treatment at temperatures higher than 500 degrees C. On the other hand,
if it is less than 0.1 µm, RTA at any temperature above 200 degrees C
will result in the bamboo structure. Copyright 2004 Published by Elsevier
B.V.
234.
Kwon, D., H. Park, et al. (2003). Recrystallization of the copper films
deposited by pulsed electroplating on ECR plasma-cleaned copper seed layers
(pt.1). 30th International Conference on Plasma Science, Jeju, South Lorea,
Korean Phys. Soc.
Cu seed layers deposited by magnetron sputtering onto tantalum nitride
barrier films were treated with an electron cyclotron resonance (ECR) plasma
to enhance Cu nucleation prior to Cu electroplating. Then, the copper films
were electroplated and annealed by rapid thermal annealing (RTA) or rapid
thermal nitridation (RTN) at various temperatures ranging from 200 to 500
degrees C. The effects of annealing on the copper films electroplated on the
hydrogen ECR plasma cleaned copper seed layers were investigated using X-ray
diffraction (XRD), electron backscattered diffraction (EBSD), and atomic
force microscopy (AFM). It appears that the copper film undergoes complete
recrystallization during annealing at a temperature higher than 400 degrees
C. The resistivity of the Cu film tends to decrease and the degree of (111)
preferred orientation tends to increase as the annealing temperature
increases. The optimum annealing condition for obtaining the film with the
lowest resistivity, the smoothest surface, and the highest degree of the
(111) preferred orientation is rapid thermal nitration (RTN) at 400 degrees
C for 120 s. The resistivity and the surface roughness of the electroplated
copper film annealed under this condition are 1.98 mu Omega -cm and 17.77
nm, respectively.
235.
Kwon, O. and S.-H. Choi (2002). Issues Related to Texture in High
Performance Steels. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
Investigations have been conducted on the texture formation in various high
performance steels, and some recent results have been summarized. An
addition of phosphorous in high strength interstitial free steels resulted
in the development of Y-fibre texture components, and the r-value was
improved. This appeared to be attibuted to the combined effects of
phosphorous on the grain size and the energy stored during cold rolling. In
low carbon steels, the planar anisotropy was reduced when Ti was added. A
visco-plastic self-consistent polycrystal model was developed to predict the
macroscopic anisotropy. The yield surface was calculated by coupling the
model with the Monte Carlo technique. The model was also applied to
calculate the yield strength anisotropy observed in high micralloyed hot
strips. The anisotrpy was shown to be reduced by decreasing the a-fibre
intensity. Analyses of the effects of pass aging on texture in silicon
steels have been attempted to determine the optimum pass aging temperature,
which was found to be 150~250°C. In a ferritic stainless steel, the
ridging phenomenon was directly assoiated with the existence of grain
clusters or grain colonies having both {001}<110> and {112}<110>
texture components.
236.
Kysar, J. W. (2002). Crack tip deformation fields in aluminum single
crystals. 2002 SEM Annual Conference & Exposition on Experimental and
Applied Mechanics, Milwaukee, WI, USA, Society for Experimental Mechanics,
Inc.
The deformation fields near the tip of a crack in ductile single crystal
media are studied experimentally. The crack, located between two single
crystals of aluminum joined by a thin ductile interlayer of tin, is
introduced via selective chemical etching and can be considered 'sharp'; the
material surrounding the tip is fully annealed. The crack is oriented in the
crystal such that a state of plane deformation is attained in the plane
normal to the crack front; this effectively renders the deformation state to
be two-dimensional. A Mode I loading is applied after which the specimen is
sectioned along its center plane and the in-plane rotation field under plane
strain conditions is mapped using Electron Backscatter Diffraction (EBSD) in
a scanning electron microscope (SEM). In essence, this measures the in-plane
component of the rotation field of the displacement gradient tensor. The
observations provide evidence of the main features of the deformation fields
predicted by continuum single crystal plasticity, especially the existence
of kink shear sector boundaries which had not been unambiguously identified
in previous studies. However in order to explain the measured change in
lattice rotation at the kink shear sector boundary, a dislocation structure
is deduced which is different than that traditionally thought to form the
kink shear sector boundary. The results have implications for analytic and
numerical simulations of plastic deformation in ductile single crystal
media, from the length scale of microns to the macroscopic length
scale.
237.
Kysar, J. W. and C. L. Briant (2002). "Crack tip deformation fields in
ductile single crystals." Acta Materialia 50(9):
2367-2380.
Crack tip deformation fields in ductile single crystal media are studied
experimentally. The crack, located between two single crystals of aluminum
joined by a thin ductile interlayer of tin, is introduced via selective
chemical etching and can be considered "sharp"; the material
surrounding the tip is fully annealed. After a Mode I loading is applied,
the specimen is sectioned and the in-plane rotation field under plane strain
conditions is mapped using Electron Backscatter Diffraction. The
observations provide evidence of the main features of the deformation fields
predicted by Rice (Mech Mater 6 (1987) 317) using continuum single crystal
plasticity, especially the existence of kink shear sector boundaries which
had not been unambiguously identified in previous studies. However to
explain the measured change in lattice rotation at the kink shear sector
boundary, an alternate dislocation structure is deduced which does not
require a high concentration of dislocation sources to be distributed along
the ray of the putative kink shear sector boundary. Based on this, a lower
bound on the dislocation density in the kink shear sector is established
experimentally. The results have implications for analytical and numerical
simulations of plastic deformation in ductile single crystal media, from the
length scale of microns to the macroscopic length scale.
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