Coercivity Enhancement by Grain Boundary Diffusion Process to Nd-Fe-B Sintered Magnets

摘要

Since the mechanism on magnetic reversal in Nd-Fe-B sintered magnets is nucleation of reversed magnetic domain, the microstructure around grain boundary is very important to achieve high coercivities. It is well known that the addition of HRE (HRE=Dy and Tb) is effective to enhance coercivities, but this results in a considerable reduction of remanence. If the magnetic anisotropy field around grain boundaries is higher than that of inner grains, the coercivity can be enhanced without a reduction of the remanence.