Application of the pattern matching approach for EBSD calibration and orientation mapping, utilising dynamical EBSP simulations

Prediction of potential pseudo-symmetry issues in the indexing of electron backscatter diffraction patterns

“…Electron backscatter diffraction (EBSD), first commercialized in the early 1990s, has become a standard technique in the arsenal of materials characterization modalities available for the study of modern engineering materials and geological materials. There are two techniques available to index EBSD patterns: Hough-based indexing (HI), in which Kikuchi bands are extracted from the patterns and their positions and orientations are analyzed to determine the orientation of the crystal lattice (Krieger Lassen, 1992;Adams et al, 1993;Krieger Lassen, 1994), and dictionary-based indexing (DI), in which complete experimental patterns are compared with simulated patterns for a discrete sampling of orientation space (Chen et al, 2015;Nolze, Winkelmann & Boyle, 2016;Nolze, Hielscher & Winkelmann, 2016;Friedrich et al, 2018). For high-quality patterns, the two indexing techniques generally produce the same results with the same angular accuracy; for patterns with a lower signal-to-noise ratio, however, the DI approach tends to be more robust.…”

Improving EBSD precision by orientation refinement with full pattern matching

“…Thus, the fine orientation features are obliterated by noise in the conventional analysis of the measured EBSPs, but these features are clearly revealed by the FPM analysis on the stored EBSPs. The improvement of orientation precision, as described by values of the 95th percentile of the KAM angle distribution, with is consistent with previous pattern matching applications on Si crystals (Friedrich et al ., 2018). The spatial resolution of about 100 nm is consistent with observations for Tungsten as discussed in Tripathi & Zaefferer (2019).…”

“…Convergence is checked by re-starting the optimisation from different initial values. The projection centre (PC) as a function of map position was calibrated by optimising both the orientation and the PC for patterns on a subgrid of 11 × 11 map points and then fitting the PC results to a linear transformation model as discussed in Friedrich et al (2018).…”

“…Orientation refinement by full pattern matching (FPM) of simulated to measured EBSPs (Nolze et al ., 2016; Nolze et al ., 2018) has been shown to improve angular resolution from the reduction in noise and improved identification of sub grains in quartzite, with an approximate improvement of precision by a factor of 3. This method has been applied to silicon crystals in a separate study (Friedrich et al ., 2018), where as a measure of angular resolution the 95th percentile of the KAM angle distribution was obtained at 0.06° (Friedrich et al ., 2018). An improvement in orientation precision when using a pattern matching approach for standard‐resolution patterns has also been discussed with respect to the orientation data delivered by different EBSD systems (Nicolaÿ et al ., 2018).…”

Comparison of Orientation Mapping in SEM and TEM

“…Indexing “spot” patterns like those that are collected at 300 kV is more mathematically demanding. Typically, a “dictionary” approach is used, where a large number of simulated patterns of different orientations are generated and compared to the experimental patterns to find the best fit (Rauch & Dupuy, 2005; Chen et al, 2015; Marquardt et al, 2017; Ram et al, 2017; Friedrich et al, 2018; Jha et al, 2018; Ram & De Graef, 2018; Charpagne et al, 2019; Foden et al, 2019; Jackson et al, 2019; Zhu et al, 2019; Kaufmann et al, 2020). In Figure 7, an example is shown for two grains.…”