Validation of kinematically simulated pattern HR-EBSD for measuring absolute strains and lattice tetragonality

Abstract

Cross correlation techniques applied to EBSD patterns have led to what has beentermed "high-resolution EBSD" (HR-EBSD). The technique yields higher accuracy orientation and strain data which is obtained by comparing a given EBSD pattern with either a real or a simulated reference pattern. Real reference patterns are often taken from a "central" position in a given grain, where it is hoped that the material is "strainfree", and they enable the determination of relative changes in orientation and strain from that present in the lattice at the reference position. Simulated patterns, on the other hand, enable comparison of the sample lattice with that of a perfect lattice, resulting in a measure of absolute strain and orientation. However, the simulated pattern method has several drawbacks, including the need to accurately specify microscope geometry, the lower fidelity / detail of simulated patterns compared with * Corresponding author: dfullwood@byu.edu A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 real patterns, and the potential for microscope-specific bias in the measured patterns (such as due to optical distortion).These drawbacks have led to much debate about the utility of the crosscorrelation technique using simulated patterns. This paper is the first to assess the accuracy of the simulated pattern method relative to the real pattern approach in a setting where accuracy can be reasonably determined, thus providing a fair assessment of the potential of the simulated pattern technique Based upon recent developments towards a standard material for assessing strain mapping techniques, this paper assesses the overall accuracy of the simulated pattern technique. Mismatch strains are calculated using both the real and simulated pattern techniques for a SiGe film deposited on a Si substrate. While the simulated pattern technique is not as accurate or precise as the real pattern technique for providing relative strains, it provides an estimate of absolute strain that is not available via the real pattern approach.

Global optimization for accurate determination of EBSD pattern centers

“…These systematic errors arise from orientation dependent slop, since the locations of the bands within a pattern affect how easily pattern shifts can be accommodated by crystal rotations. This may present difficulties for certain datasets, such as those involving single crystal specimens, which have often been used to study the accuracy of pattern center determination algorithms [14,32,34].…”

Pattern matching analysis of electron backscatter diffraction patterns for pattern centre, crystal orientation and absolute elastic strain determination – accuracy and precision assessment

“…For the accurate PC localisation for absolute strain analysis via simulation based HR-EBSD, Fullwood et al [14] and Alkorta et al [15] determined the PC position in a very similar way. First, an initial guess of the PC position and crystal orientation is given and then the corresponding simulated pattern is generated.…”

Simulation of kinematic Kikuchi diffraction patterns from atomistic structures

“…Despite these limitations, the positions of the diffraction bands from kinematic Kikuchi and EBSD patterns are not influenced by multiple diffraction events and these positions have been used for orientation identification as well as for measurement of lattice strain and distortion [42] . Dynamic pattern simulation would be more accurate than the present method, but to the authors’ knowledge this is the only known method that can simulate Kikuchi patterns of extended defects within large-scale atomic models.…”