High Performance Rare Earth Bonded Magnets Using lnterparticle Interactions

Abstract

High-performance bonded magnets composed of Sm₂Co₁₇ powder mixed with Sm₂Fe₁₇N_x powder were developed. This is an important technology using the magnetostatic interaction between Sm₂Co₁₇ and Sm₂Fe₁₇N_x particles. The interparticle interaction (IPI) is estimated by the mean field approximation. IPI suppresses the magnetization reversal of Sm₂Fe₁₇N_x particles, and increases the alignment of both types of magnetic particles. The amount of IPI is influenced by the magnetic properties of each powder, which necessarily must be homogeneously dispersed. With proper adjustment of the preparation conditions, the magnetic properties of mixed bonded magnets are B_r=10.1 kG,_iH_c= 12.6 kOe, and (BH)_max=22.6 MGOe. The temperature coefficients of B_r and _iH_c in this magnet are -0.05%/°C and -0.26%/°C, respectively, which are comparable with those of Sm₂Co₁₇.