LAUSR

Abstract The detwinning evolution of hierarchically structured martensitic variants in a directionally solidified non-modulated Ni-Mn-Ga alloy has been investigated by applying uniaxial compression parallel to the parent [001] A orientation with a cumulative strain of 3%, 7.3% and 10%, respectively. After each compression, the crystallographic orientations are obtained by manually indexing the Kikuchi patterns and the corresponding twinning relationships between the variants are also calculated. The results indicate that for both the intra-plate major-minor variants and inter-plate major-major variants, the detwinning occurs on the twins with high Schmid factor, resulting in a martensite only composed of favorable variants with [110] NM orientation parallel to the compression direction.