Preparation and characterization of ferromagnetic shape memory alloys

Ferromagnetic shape memory (FSM) alloy of Ni2MnGa was prepared by melt casting technique. Equiaxed grained and columnar structures were obtained. The structure of the cast alloy revealed a twinned structure. In situ study of the structure during heating revealed the martensitic to austenitic transformation taking place in the temperature range of 160–300 °C. At temperatures above 550 °C, a second reaction was found to take place. The activation energy for this reaction was determined to be 80 kJ/mol by differential scanning calorimeter (DSC). The field-induced strain for the material in the polycrystalline form was 0.18×10−4 at room temperature.