Automated Twin Identification Technique for Use with Electron Backscatter Diffraction

Historically, twinning classification has been obtained by optical microscopy, bulk x-ray and neutron diffraction, and transmission electron microscopy (TEM). Recent research has shown that automated electron backscatter diffraction (EBSD) can be used to quantify twin content and thereby greatly improve the reliability of twinning statistics. An automated twin identification technique for use with EBSD has facilitated a greater understanding of deformation twinning in materials. The key features of this automated framework are the use of the crystallographic definition of twin relationships, and the correct identification of the parent orientation in a parent/twin pair. The complex nature of the parent/twin interactions required the use of a voting scheme to correctly identify parent orientations. In those few cases where the voting scheme was unable to determine parent orientation (< 2%) the algorithm allows for manual selection. Twin area fractions are categorized by operative twin systems along with secondary and tertiary twinning. These statistics are reported for deformation and annealing twin populations in deformed a-zirconium and asannealed 316L stainless steel, respectively. These improved twin statistics can help provide insight into the effect of deformation processes on microstructural evolution, as well as provide validation of plasticity models for materials that exhibit deformation twinning.