Quantification of multiple twinning in face centred cubic materials

摘要

Grain boundary engineering (GBE) aims at optimizing the properties of face centred cubic materials with low stacking fault energy by creating a high content of special twin boundaries. Quantifying twinning and its parameters, such as the twin related domains (TRDs) and the related ?3~n special grain boundaries, is thus of prime importance for GBE. A method is presented in detail to treat the electron backscatter diffraction (EBSD) maps. The TRDs are automatically reconstructed, the twinning chain trees of the TRDs are determined and represented with fractal graphs, and the ?3~n grain boundaries are identified up to order n = 12. New parameters, such as the numbers of grains (N_g), the lengths of the longest chain (LLC), the twinning polysynthesism (p) and twinning anisotropy (a) factors, are also calculated. Examples have been given for two nickel superalloys, a silicon ingot, a cadmium telluride film, and a copper thin film.