Phase Transformation of Ni2MnGa Made by the Spark Plasma Sintering Method

Heusler compound Ni2MnGa was prepared by the spark plasma sintering (SPS) technique. The sintering was done with a maximum pressure of 80 MPa and a maximum temperature of 1173 K for 300∼600 s. The relative density of the as-sintered alloy was 99.6%. The grinding-induced stress results in the suppression of phase transformation in the as-sintered alloy. Heat treatment was subsequently performed at 1073 K for 864 ks in vacuum, slowly cooled for recovering the phase transformation. After heat treatment the martensitic transformation temperatures, M s , M f , A s , A f , of the sintered alloy can be determined as 235, 220, 239 and 254 K respectively.