Modification of Ni–Mn–Ga ferromagnetic shape memory alloy by addition of rare earth elements

Effect of addition of rare earth elements, such as, Nd, Sm and Tb, was investigated on various properties of Ni–Mn–Ga ferromagnetic shape memory alloys (SMAs). The solubility of the rare earth in the L21 phase was found to be very low, most likely less than 0.1 mol%. Insolvable rare earth segregated into subgrain boundaries or grain boundaries to form precipitates. Phase transformation behavior and the structure of martensite phase exhibit a similar dependence on valence electron concentration to those in ternary Ni–Mn–Ga alloys. It was revealed that the addition of rare earth significantly improves the compressive ductility of the alloy.