PHASE-TRANSITIONS IN THE FERROMAGNETIC-ALLOYS NI2-XGA(XMN1)

The phase diagram of the cubic ferromagnetic shape-memory alloy Ni2+xM n1-xGa is constructed theoretically for the case when the Curie temper ature is close to the structural transition temperature. This diagram agrees well with the experimental data obtained from resistance and ma gnetic susceptibility measurements. It is shown that the transition fr om the paramagnetic cubic phase to the ferromagnetic tetragonal phase can be second-order or first-order. (C) 1998 American Institute of Phy sics.