Structure and properties of rapidly-solidified iron-platinum and iron-palladium alloys

Rapid solidification techniques and systematic heat treatment have been employed to vary the microstructure of equiatomic Fe-Pt and Fe-Pd alloys to gain a better understanding of the fundamental processes controlling the magnetic properties in this genre of alloy. Preliminary results on the Fe-Pd alloy indicate that the magnetically hardened material is fully ordered and exhibits a well-developed polytwinned state. Melt-spinning resulted in an increase in coercivity in the Fe-Pd alloy over the bulk material by a factor of about two. It is suggested that this enhanced magnetic hardness stems from microstructural refinement within the polytwinned state. Prolonged aging of both melt-spun and bulk Fe-Pd alloys leads to very little change of coercivity. This is suggested to be related to the behavior of the polytwinned state during prolonged aging in which the twin cluster size essentially remains constant. The initial results on the Fe-Pt alloy indicate that the details of the mechanism of hardening in this alloy may be somewhat different from those in the Fe-Pd system, although both develop the polytwinned state after prolonged aging