Magnetic properties and microstructure of Fe-Pt based alloys

Summary form only given. The Fe-Pt alloys have a complete solid solubility range at high temperature with a disordered face-centred cubic (fcc) AuCu type structure in which the Fe and Pt atoms are statistically distributed over the crystallographic sites. For alloys around the equiatomic composition, ageing at lower temperatures leads to a transformation to an ordered L1/sub 0/ type face-centred tetragonal (fct) structure with alternating layers of Fe and Pt. This tetragonal phase gives rise to a strong increase of the magnetic hardness of the alloys, which makes them suitable for permanent magnets to be used, for instance, in dentures. We have studied the effect of isothermal annealing on the hard magnetic properties and the microstructure of Fe-Pt based alloys containing small amounts of Nb and Al.