Crystallographic analysis of the B2 → B19′ martensite transformation in titanium nickelide

A phenomenological theory of martensite transformation is used to determine (select) the mechanism of B2 → B19′ transformation. The most realistic mechanism corresponds to the minimum additional rotation of a martensite plate needed to maintain the invariance of the habit plane. Equal values of the macroscopic shear direction and extent, the habit plane, the deformation for the invariant lattice, and the general deformation of shape are obtained for four different deformations. However, the supplementary rotation for each option is different. The minimum angle of rotation is observed for deformation by a martensite transformation with {21-1}B2 plane shear in the 〈-11-1〉 direction.