Martensitic transformation and magnetocaloric properties of Sn doping Mn-Ni-Ga alloys

The effects of Sn addition on phase transformation behavior and magnetocaloric properties of Mn₅₀Ni₂₅Ga_25−xSn_x (x=0, 0.1, 0.5, 1 and 2 at%) alloys were investigated in this work. The results show that the addition of Sn reduces the structural transformation temperatures. It is found that the second phase exists in the austenite matrix of the as-casted alloys at room temperature. After being annealed at 1073 K for 48 h, the precipitates totally soluted into the matrix. Magnetization measurements indicate that the saturation magnetizations of the alloys increase significantly with increase in Sn contents. In addition, the ΔM/ΔS obviously increases with increase in the Sn contents, implying the higher efficiency shift of the martensitic transformation temperature under the magnetic field.