Phase Relations in the Ni-Mn-Ga Ternary System and Aging Effect on Shape Memory Properties of Ferromagnetic Ni_2MnGa Sputtered Films

摘要

Isothermal sections of the Ni-Mn-Ga ternary phase diagram at 1073 and 1273K were investigated over a wide range of alloy compositions.The range of the beta-Ni_2MnGa phase,its equilibria with the gamma-(Mn,Ni),alpha'-Ni_3Ga,and gamma-Ni_3Ga_2 phases,and the liquidus and solidus lines were determined experimentally.The aging effect on the shape memory effect(SME)of Ni_2MnGa sputtered films was also investigated.The two-way SME of the constraint-aged films was confirmed by the temperature change.