Time-dependent dynamic response of martensite in Ni-Mn-Ga magnetic shape memory alloys to stress caused by constant magnetic field

This work presents the original experimental results concerning study of new phenomenon – time-dependent behaviour under a constant magnetic field and some effects recently found concerning the kinetics of stress relaxation in Ni-Mn-Ga alloys. Three non-stoichiometric Ni-Mn-Ga alloys, producing large magnetic shape memory effect (MSME) up to 5% at room temperature, were investigated. It was found from the time dependence of the magnetic field induced strain at constant magnetic field and set temperature that the material gradually deforms under constant magnetic field in a manner analogous to mechanical creep under constant applied compressive stress