Effect of aging on phase transformation and magnetic properties of Mn53Ni25Ga22 ferromagnetic shape memory alloy

The Mn53Ni25Ga22 ferromagnetic shape memory alloy has been aged at various temperatures for 3 h, and the martensitic transformation and magnetic properties have been investigated by differential scanning calorimetry (DSC) and the Physical Property Measurements System (PPMS, Quantum Design). The results show that precipitation has an obvious effect on martensitic transformation temperatures, Curie temperatures and saturation magnetization. Aging greatly affects transformation temperatures due to modified composition of the matrix. Martensitic transformation temperature, Curie temperatures first decreased and then increased with increase of aging temperature, reaching their minimum values at the aging temperature of 773 K. The saturation magnetizations first rapidly increase and then rapidly decrease with increase of aging temperature, reaching the maximum value at 773 K. It can be concluded that appropriate ageing treatment can enhance the saturation magnetization of Mn53Ni25Ga22 alloy.