Time-dependent magnetostrain effect and stress relaxation in the martensitic phase of Ni-Mn-Ga

A simple theoretical model of the time-dependent magnetostrain effect in the Ni–Mn–Ga shape memory alloy is proposed. According to the model, a long-time response of the alloy to the magnetic field application is caused by the relaxation of field-induced mechanical stresses, and therefore, the field-induced strains depend exponentially on time. An agreement between the theoretical and experimental time dependencies of the field-induced strains is ascertained.