2-DIMENSIONAL AND 3-DIMENSIONAL CALCULATION OF REMANENCE ENHANCEMENT OF RARE-EARTH BASED COMPOSITE MAGNETS (INVITED)

Micromagnetic calculations using a finite element technique rigorously describe the properties of novel, isotropic rare-earth-based composite magnets. Numerical results obtained for a composite material of Nd2Fe 14B, SmCo5 or Sm2(Fe0.8Co 0.2)17N2.8 and α-Fe particles show that remanence, coercivity, and coercive squareness sensitively depend on microstructural features. Interparticle exchange interactions enhance the remanence by about 60% with respect to noninteracting particles for a mean-grain size approaching the exchange length of the soft magnetic phase and a significant percentage of α-Fe. On the other hand, exchange interactions between the phases suppress the nucleation of reversed domains and thus preserve a high coercive field. Therefore, optimally structured, isotropic composite magnets show remarkably high energy products exceeding 400 kJ/m3.