Inferential statistics of electron backscatter diffraction data from within individual crystalline grains

2010 ◽  
Vol 43 (6) ◽  
pp. 1338-1355 ◽  
Author(s):  
Florian Bachmann ◽  
Ralf Hielscher ◽  
Peter E. Jupp ◽  
Wolfgang Pantleon ◽  
Helmut Schaeben ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Orientation Distribution ◽  
Numerical Determination ◽  
Spatial Statistical Analysis ◽  
Spatial Reference ◽  
Electron Backscatter ◽  
The Mean ◽  
Backscatter Diffraction ◽  
Crystallographic Orientations

Highly concentrated distributed crystallographic orientation measurements within individual crystalline grains are analysed by means of ordinary statistics neglecting their spatial reference. Since crystallographic orientations are modelled as left cosets of a given subgroup of SO(3), the non-spatial statistical analysis adapts ideas borrowed from the Bingham quaternion distribution on {\bb S}^3. Special emphasis is put on the mathematical definition and the numerical determination of a `mean orientation' characterizing the crystallographic grain as well as on distinguishing several types of symmetry of the orientation distribution with respect to the mean orientation, like spherical, prolate or oblate symmetry. Applications to simulated as well as to experimental data are presented. All computations have been done with the free and open-source texture toolboxMTEX.

A Dictionary Approach to Electron Backscatter Diffraction Indexing

2015 ◽  
Vol 21 (3) ◽  
pp. 739-752 ◽  
Author(s):  
Yu H. Chen ◽  
Se Un Park ◽  
Dennis Wei ◽  
Greg Newstadt ◽  
Michael A. Jackson ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Orientation Distribution ◽  
Polycrystalline Materials ◽  
Dictionary Matching ◽  
Binary Decision Tree ◽  
Electron Backscatter ◽  
Dense Grid ◽  
The Mean ◽  
Von Mises ◽  
Backscatter Diffraction

AbstractWe propose a framework for indexing of grain and subgrain structures in electron backscatter diffraction patterns of polycrystalline materials. We discretize the domain of a dynamical forward model onto a dense grid of orientations, producing a dictionary of patterns. For each measured pattern, we identify the most similar patterns in the dictionary, and identify boundaries, detect anomalies, and index crystal orientations. The statistical distribution of these closest matches is used in an unsupervised binary decision tree (DT) classifier to identify grain boundaries and anomalous regions. The DT classifies a pattern as an anomaly if it has an abnormally low similarity to any pattern in the dictionary. It classifies a pixel as being near a grain boundary if the highly ranked patterns in the dictionary differ significantly over the pixel’s neighborhood. Indexing is accomplished by computing the mean orientation of the closest matches to each pattern. The mean orientation is estimated using a maximum likelihood approach that models the orientation distribution as a mixture of Von Mises–Fisher distributions over the quaternionic three sphere. The proposed dictionary matching approach permits segmentation, anomaly detection, and indexing to be performed in a unified manner with the additional benefit of uncertainty quantification.

Electron backscatter diffraction determination of grain orientation and constituent phases

1999 ◽  
Vol 4 (2) ◽  
pp. 174-174
Author(s):  
Chen Xiaomei ◽  
Liu Jing ◽  
Wang Jianbo ◽  
Zhang Ruikang ◽  
Wang Dahai ◽  
...  
Keyword(s):  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Diffraction Determination ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Application of Electron Backscatter Diffraction for Crystallographic Characterization of Tin Whiskers

2012 ◽  
Vol 18 (4) ◽  
pp. 876-884 ◽  
Author(s):  
Joseph R. Michael ◽  
Bonnie B. McKenzie ◽  
Donald F. Susan
Keyword(s):  
Electron Backscatter Diffraction ◽  
Growth Direction ◽  
Tin Whiskers ◽  
Physical Growth ◽  
Final Choice ◽  
Advantages And Disadvantages ◽  
Electron Backscatter ◽  
Backscatter Diffraction

AbstractUnderstanding the growth of whiskers or high aspect ratio features on substrates can be aided when the crystallography of the feature is known. This study has evaluated three methods that utilize electron backscatter diffraction (EBSD) for the determination of the crystallographic growth direction of an individual whisker. EBSD has traditionally been a technique applied to planar, polished samples, and thus the use of EBSD for out-of-surface features is somewhat more difficult and requires additional steps. One of the methods requires the whiskers to be removed from the substrate resulting in the loss of valuable physical growth relationships between the whisker and the substrate. The other two techniques do not suffer this disadvantage and provide the physical growth information as well as the crystallographic growth directions. The final choice of method depends on the information required. The accuracy and the advantages and disadvantages of each method are discussed.

An Investigation of Microtexture Evolution in an AlMgSi Alloy Processed by High-Pressure Torsion

2011 ◽  
Vol 702-703 ◽  
pp. 165-168 ◽  
Author(s):  
Aicha Loucif ◽  
Thierry Baudin ◽  
François Brisset ◽  
Roberto B. Figueiredo ◽  
Rafik Chemam ◽  
...  
Keyword(s):  
Grain Size ◽  
High Pressure ◽  
Distribution Function ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
Orientation Distribution ◽  
Homogeneous Microstructure ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Almgsi Alloy

This investigation uses electron backscatter diffraction (EBSD) to study the development of microtexture with increasing deformation in an AlMgSi alloy having an initial grain size of about 150 µm subjected to high pressure torsion (HPT) up to a total of 5 turns. An homogeneous microstructure was achieved throughout the disc sample at high strains with the formation of ultra-fine grains. Observations based on orientation distribution function (ODF) calculation reveals the presence of the torsion texture components often reported in the literature for f.c.c. materials. In particular, the C {001}<110> component was found to be dominant. Furthermore, no significant change in the texture sharpness was observed by increasing the strain.

EBSD Characterization of Pure Iron Deformed by ECAE

2010 ◽  
Vol 638-642 ◽  
pp. 1995-2000 ◽  
Author(s):  
Reny Angela Renzetti ◽  
M.J.R. Sandim ◽  
Hugo Ricardo Zschommler Sandim ◽  
K.T. Hartwig ◽  
Heide H. Bernardi ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Softening Mechanism ◽  
Resolution Electron ◽  
Mean Grain Size ◽  
Electron Backscatter ◽  
Deformed State ◽  
The Mean ◽  
Backscatter Diffraction

Polycrystalline iron was deformed by eight ECAE passes using the route Bc to a total strain of 9.2. After deformation the material was annealed at temperatures up to 800oC. Scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD) were used to characterize both deformed and annealed structures. In the as-deformed state, the mean grain size is 650 nm and the volume fraction of high angle boundaries (VHAB) is 56%. Upon annealing there is a pronounced softening above 300oC. At the beginning of recrystallization, at about 400oC, the VHAB increases to 71%. The results indicate that discontinuous recrystallization is the main softening mechanism in severely deformed iron.

Denoising of crystal orientation maps

2019 ◽  
Vol 52 (5) ◽  
pp. 984-996 ◽  
Author(s):  
R. Hielscher ◽  
C. B. Silbermann ◽  
E. Schmidl ◽  
Joern Ihlemann
Keyword(s):  
Variational Methods ◽  
Crystal Orientation ◽  
Electron Backscatter Diffraction ◽  
Sliding Window ◽  
Orientation Data ◽  
Kernel Average Misorientation ◽  
Orientation Maps ◽  
Electron Backscatter ◽  
Backscatter Diffraction

This paper compares several well known sliding-window methods for denoising crystal orientation data with variational methods adapted from mathematical image analysis. The variational methods turn out to be much more powerful in terms of preserving low-angle grain boundaries and filling holes of non-indexed orientations. The effect of denoising on the determination of the kernel average misorientation and the geometrically necessary dislocation density is also discussed. Synthetic as well as experimental data are considered for this comparison. The examples demonstrate that variational denoising techniques are capable of significantly improving the accuracy of properties derived from electron backscatter diffraction maps.

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