Preparation and Properties of the Ni₂MnGa Magnetic Shape Memory Alloy

The polycrystalline Ni_48.2Mn_22.4Ga_29.4 alloys were prepared by means of melting in argon arc furnace. X-ray diffraction pattern indicates a fcc cubic structure with a lattice parameter of 0.5822nm at room temperature. The phase transformation temperatures were: 1°C for martensite start temperature, -11°C for martensite finish temperature, 3°C for austenite start temperature and 11°C for austenite start temperature, respectively. The results showed that the effect of magnetic field on the strains increases with the decrease of temperature. A strain of 2.1 x10^-4 was obtained with an applied magnetic field of 5kOe at -66°C.