Radially induced magnetic anisotropy in Fe-Cr-Co permanent magnets

Fe-Cr-Co magnets with radial anisotropy were developed by rotating samples in a magnetic aging furnace. The anisotropy is altered by the applied magnetic field strength. The Fe-25 wt. %Cr-12 wt. %Co-0.5 wt. %Ti alloy aged in a magnetic field of 100 Oe yields the magnetic properties of (BH)_max=24 kJ m^-3 (3 MGOe) and _iH_c=48 kA m^-1 (600 Oe) parallel to radial direction, which are higher than those of (BH)_max=7 kJ m^-3 (0.9 MGOe), _iH_c=33 kA m^-1, measured parallel to the circumferential direction. The increment of the applied magnetic field over 200 Oe alters the radial anisotropy into a circumferential one. Microstructural studies indicate that the iron-rich phase is elongated parallel to the direction of induced anisotropy. Computations of the magnetic flux distribution in disk samples confirm the experimental observations.