Martensite stabilisation in single crystalline Ni-Mn-Ga and Ni-Mn-Sn magnetic shape memory alloys

Martensite stabilization in Ni-Mn-Ga and Ni-Mn-Sn single crystals was induced by mechanical training. The degree of stabilization differs between Ni-Mn-Ga and Ni-Mn-Sn (ΔT = 28 K), what is attributed to a disparity in the twinning stress affecting also transformation morphology. Upon martensitic transformation multiple site nucleation is favoured by a larger twinning stress in Ni-Mn-Sn in contrast to a planar phase front movement in Ni-Mn-Ga.