FePt alloy has long been known as a very good kind of permanent magnet material, and FePt bulk has not applied well due to the expensive cost price, in the meanwhile, FePt permanent magnet material plays more and more important role with the development of magnetic recording media and nanotechnology.
Fe-Pt binary alloy phase diagram indicates that the phase structure and magnetic performance of Fe-Pt binary alloy vary as the composition changes. L10-FePt phase is a hard magnetic phase which has the body-centered tetragonal structure. Both L12 Fe3Pt and L12 FePt3 are soft magnetic phase which has the face-centered cubic structure. L10-FePt ordered alloy has many merits include:
- Relatively higher Kuvalue which maintains superior thermal stability when grain size between 3 and 5nm.
- Domain wall is narrow, and even small defect of grain boundary will enhance pinning effect.
- Saturation magnetization is relatively larger and thus conductive to reduce the dimension of the single domain particle.
- The theoretical (BH)max value can reach 1460 kJ/m3.
- Excellent anti-corrosion and anti-oxidation capacity.
Research of FePt permanent magnet material is mainly focused on the thin film and nanoparticle. The most promising application area of FePt is the magnetic recording. For FePt nanoparticle, researchers have been basically achieved morphological and size control through lots of research work.
