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 Tc and martensitic transition starting temperature Ms increase, while the saturation magnetization Is decreases with increasing Co content in the series of Ni51Fe22−XCoXGa27 alloys. On the other hand, the values of both Tc and Is increase and Ms decrease with increasing Co content in the series of Ni54−XFe19CoXGa27 alloys. Tc and Is 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.