Remanence enhancement based on L1 ordering in Fe–Pt permanent magnets

This study investigated the relationship between the hard magnetic properties and microstructure of bulk FePt magnets, which can potentially be used in dental prostheses. A high level of remanence was obtained in a Fe–39.5 mol %Pt alloy aged at 873 K, in which minute FePt ordered domains of about 10 nm in size were uniformly created. The change in the maximum energy product of this alloy was in good agreement with the level of remanence: they both decreased with increasing aging time, and the size of the ordered domains gradually grew. The remanence ratio of as-quenched Fe–40 mol %Pt magnet has been estimated at 0.69, despite the morphological isotropy of the magnet. Remanence enhancement occurred in an FePt single phase without the presence of the magnetically soft disordered phase, since the spring back phenomenon was not observed in the recoil curve measurements, and the entire area was covered with minute FePt ordered domains. The hard magnetic properties were enhanced at the optimum ordered domain size of about 10 nm. This study found that the ordered domains behaved as a single magnetic domain particle and improved remanence through intergranular exchange interaction.