Defect Structure and Martensitic Transformation Crystallography in Ni2MnGa Alloy
Ferromagnetic shape memory alloys can produce large strains in a magnetic field by twin boundary motion. The mobility of parent-martensite inter-phase interfaces and twin-twin inter-variant boundaries is closely related to their interfacial structures and the mechanism of migration, therefore a thorough understanding of its nature is of importance. A physical model of the structure of parent-martensite interface has been developed recently based on dislocation theories and topological arguments. On the basis of the topological model, the present work performs a theoretical study of the defect structure of the martensitic interface, and the transformation crystallography in Ni2MnGa alloy. The habit plane, i.e., the parent-martensite interface plane was determined to be (-0.761, -0.054, -0.646)P for the parent crystal index frame, and (-0.818, 0.067, -0.571)M for the martensite frame. The habit plane inclination angle is 5.945° and 5.953° with respect to the terrace plane in the parent and martensite crystals, respectively.
Chengming Li, Chengbao Jiang, Zhiyong Zhong and Yichun Zhou
Z. Z. Wei et al., "Defect Structure and Martensitic Transformation Crystallography in Ni2MnGa Alloy", Materials Science Forum, Vol. 687, pp. 463-466, 2011