Microstructure and Magnetic Properties of MM-Fe-B Magnets Prepared by Spark Plasma Sintering

High-density isotropic permanent magnet blocks were prepared using nanocrystalline rapidly quenched MM2.2Fe14B strip powder through spark plasma sintering (SPS) technology. This study investigated the impact of the sintering process on the phase composition, microstructure, and magnetic properties of MM-Fe-B SPS magnets. The results show that with the increase of sintering temperature, the porosity of the magnet decreases and the density of the magnet increases gradually. At a sintering temperature of 700 °C/50 MPa/5 min, the magnet exhibited relatively small grain size, and superior comprehensive performance, including coercivity ${H} _{\text {cj}}$ = 525 kA/m, remanence ${B} _{r}$ = 0.76 T, maximum magnetic energy product (BH) $_{\max }$ = 82 kJ/m3. Isotropic nanocrystalline MM-Fe-B based magnets were prepared by SPS, which provides a new guidance for the research and development of permanent magnet materials prepared by ionic mixed rare earth.