Interaction mechanism, magnetic properties and microstructure of Ce-Fe-B/Alnico spark plasma sintered magnets

By combining rare earth-based Ce-Fe-B and rare earth free Alnico powders, composite Ce-Fe-B/Alnico spark plasma sintered (SPS) magnets have been fabricated and reported for the first time. It is observed that the two phases exit in the alloys interacting magnetostatically. The Alnico phase constitutes α₁ and α₂ phases as a consequence of spinodal decomposition process, while the Ce-Fe-B phase contained Ce₂Fe₁₄B and CeFe₂ phases. By increasing the content of Alnico phase, the remanence magnetization and the maximum energy density of the composite alloys increased owing to the higher saturation magnetization of Alnico phase. Magnetic properties, such as remanence magnetization J_s = 0.93 T, intrinsic coercivity H_cj = 202 kA/m and maximum energy density (BH)_max = 19.8 kJ/m³ were obtained in spark plasma sintered composite magnets containing 15 wt% Alnico. The recoil loops demonstrated the presence of anisotropy variations in the alloys specifically at high applied magnetic field. Analysis of the Curie temperature and elemental analysis validated that the constituent phases of SPS magnets exist in the alloys. This work may shed light on the development of composite magnets with distinct phases and enhanced magnetic properties.