Effect of γ precipitates on martensitic transformation and magnetic properties in aged Mn–Ni–Ga alloys

Abstract

Multiple martensitic transformation peaks were observed from differential scanning calorimetry curves in aged Mn50Ni25Ga25 alloys in which transformation temperature varied with aging temperature. The magnetization and coercivity were enhanced as a result of aging above magnetic transition temperature. A maximum magnetization up to 54emu∕g and a magnetization difference between two phases of 28emu∕g was achieved in the alloy aged at 873K. However, coercivity as large as 1.2kOe was obtained in 573K aged alloy, with a high saturation field, which can be understood in terms of domain wall pinning.