Differently mobile twin boundaries and magnetic shape memory effect in 10 M martensite of Ni–Mn–Ga

We investigated twin boundaries with sharply different mobility or twinning stress in five-layered modulated (10 M) martensite of Ni–Mn–Ga exhibiting magnetic shape memory effect or magnetically induced reorientation. Different mobility is ascribed to the different microstructures of the macrotwin planar interface. In monoclinic approximation the mobile boundaries are of Type I and Type II with complex microstructure of adjoining variants. These boundaries respond differently to magnetic field. For Type II boundary the reorientation takes place at very low field 250 Oe.