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Title: Resolving pseudosymmetry in γ-TiAl using cross-correlation electron backscatter diffraction with dynamically simulated reference patterns

Abstract

Pseudosymmetry is a phenomenon that occurs when grains with different lattice parameters produce nearly identical diffraction patterns such that conventional electron backscatter diffraction (EBSD) techniques are unable to unambiguously differentiate the lattice orientations. This commonly occurs in materials with near-unity tetragonality, such as γ-TiAl. The current study uses cross-correlation EBSD to resolve pseudosymmetry in γ-TiAl. Three dynamically simulated reference patterns are generated for each point in the scan, one for each of the three potential pseudosymmetric orientations, which are subsequently correlated with the original pattern using six different methods in order to identify the correct orientation. The methods are first applied to a scan of dynamically simulated patterns, which is used to evaluate the sensitivity of the method to pattern resolution, pattern noise and pattern center error. It was determined that all six methods were 100% successful up to about 13 µm of pattern center error and pattern resolutions of about 80 × 80 pixels, and hence the methods were applied to an experimental sample of lamellar γ-TiAl. A hybrid combination of two of the methods was shown to successfully select the correct pseudosymmetry for about 96% of the points in the scan, improving upon the 70% accuracy of the Hough-basedmore » methods for the current study and 90% accuracy for previous studies resolving pseudosymmetry in lamellar γ-TiAl.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Brigham Young Univ., Provo, UT (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1541441
DOE Contract Number:  
SC0012587
Resource Type:
Journal Article
Journal Name:
Journal of Applied Crystallography (Online)
Additional Journal Information:
Journal Volume: 51; Journal Issue: 3; Journal ID: ISSN 1600-5767
Publisher:
International Union of Crystallography
Country of Publication:
United States
Language:
English
Subject:
Chemistry; Crystallography

Citation Formats

Jackson, Brian, Fullwood, David, Christensen, Jordan, and Wright, Stuart. Resolving pseudosymmetry in γ-TiAl using cross-correlation electron backscatter diffraction with dynamically simulated reference patterns. United States: N. p., 2018. Web. doi:10.1107/s1600576718003849.
Jackson, Brian, Fullwood, David, Christensen, Jordan, & Wright, Stuart. Resolving pseudosymmetry in γ-TiAl using cross-correlation electron backscatter diffraction with dynamically simulated reference patterns. United States. doi:10.1107/s1600576718003849.
Jackson, Brian, Fullwood, David, Christensen, Jordan, and Wright, Stuart. Fri . "Resolving pseudosymmetry in γ-TiAl using cross-correlation electron backscatter diffraction with dynamically simulated reference patterns". United States. doi:10.1107/s1600576718003849.
@article{osti_1541441,
title = {Resolving pseudosymmetry in γ-TiAl using cross-correlation electron backscatter diffraction with dynamically simulated reference patterns},
author = {Jackson, Brian and Fullwood, David and Christensen, Jordan and Wright, Stuart},
abstractNote = {Pseudosymmetry is a phenomenon that occurs when grains with different lattice parameters produce nearly identical diffraction patterns such that conventional electron backscatter diffraction (EBSD) techniques are unable to unambiguously differentiate the lattice orientations. This commonly occurs in materials with near-unity tetragonality, such as γ-TiAl. The current study uses cross-correlation EBSD to resolve pseudosymmetry in γ-TiAl. Three dynamically simulated reference patterns are generated for each point in the scan, one for each of the three potential pseudosymmetric orientations, which are subsequently correlated with the original pattern using six different methods in order to identify the correct orientation. The methods are first applied to a scan of dynamically simulated patterns, which is used to evaluate the sensitivity of the method to pattern resolution, pattern noise and pattern center error. It was determined that all six methods were 100% successful up to about 13 µm of pattern center error and pattern resolutions of about 80 × 80 pixels, and hence the methods were applied to an experimental sample of lamellar γ-TiAl. A hybrid combination of two of the methods was shown to successfully select the correct pseudosymmetry for about 96% of the points in the scan, improving upon the 70% accuracy of the Hough-based methods for the current study and 90% accuracy for previous studies resolving pseudosymmetry in lamellar γ-TiAl.},
doi = {10.1107/s1600576718003849},
journal = {Journal of Applied Crystallography (Online)},
issn = {1600-5767},
number = 3,
volume = 51,
place = {United States},
year = {2018},
month = {4}
}