Phase transformation of Ni2MnGa made by the spark plasma sintering method

Abstract

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 approx. 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 assintered 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, Ms, Mf, As, Af, of the sintered alloy can be determined as 235, 220, 239 and 254 K respectively.