FePt hard magnets

The FePt alloys have recently attracted considerable attention due to their excellent intrinsic magnetic, chemical and mechanical properties. Their possible usage ranges from permanent magnets for special applications (e.g. in micro-electro-mechanical systems, magnetic MEMS, and in aggressive environments) to ultra-high density magnetic storage media. The article describes general aspects concerning the phase formation and magnetic properties of materials based on the L1(0) FePt phase. Both thin film and bulk approaches are considered. The production of bulk nanocrystalline Fe100-xPtx powders by mechanical alloying and subsequent annealing is described. Various combinations of phases, away from thermodynamic equilibrium, have been obtained using this technique.