Search

Summary The prior β grain structure and orientations in the central stir zone of friction stir–processed Ti–6Al–4V were reconstructed from measured α phase orientations obtained by three-dimensional serial sectioning in a dual-beam focused ion beam scanning electron microscope. The data were processed to obtain the α colony and β grain size distributions in the volume. Several β grains were individually analysed to determine the total number of unique α variants and the respective volume fractions of each. The analysis revealed that some grains experienced overwhelming variant selection (i.e. one variant dominated) whereas other β grains contained a more evenly distributed mixture of all 12 variants.

Summary A method for automatically aligning consecutive data sets of large, two-dimensional multi-tile electron backscatter diffraction (EBSD) scans with high accuracy was developed. The method involved first locating grain and phase boundaries within search regions containing overlapping data in adjacent scan tiles, and subsequently using cross-correlation algorithms to determine the relative position of the individual scan tiles which maximizes the fraction of overlapping boundaries. Savitzky-Golay filtering in two dimensions was used to estimate the background, which was then subtracted from the cross-correlation to enhance the peak signal in samples with a high density of interfaces. The technique was demonstrated on data sets with a range of interface densities. The equations were implemented as enhancements to a recently published open source code for stitching of multi-tile EBSD data sets.