Influence of Co Addition on Martensitic and Magnetic Transitions in Ni-Fe-Ga β Based Shape Memory Alloys

Abstract

The effect of Co addition on the martensitic transition and magnetic properties of the Ni-Fe-Ga β alloys is investigated. The values of both the Curie temperature T_c and martensitic transition starting temperature M_s increase, while the saturation magnetization I_s decreases with increasing Co content in the series of Ni₅₁Fe_22−XCo_XGa₂₇ alloys. On the other hand, the values of both T_c and I_s increase and M_s decrease with increasing Co content in the series of Ni_54−XFe₁₉Co_XGa₂₇ alloys. T_c and I_s show a strong dependence on the average magnetic valence number Zm. Consequently, Co is an effective element to control both the martensitic and the magnetic transition temperatures.