Comparative Study of Magnetization Mechanisms in Newly Prepared High Coercive Dy-free Nd-Fe-B Sintered Magnets and in Sm_2Co_(17) Type Magnets

摘要

The newly prepared Dy-free Nd-Fe-B sintered magnets (NPM) show the comparatively high coercivity of about 20kOe. The average grain sizes (D_(AVE)) of the NPM are around 1.9μm and the domain widths (d_D) are about a half of the D_(AVE). In the final stage of magnetization process, a characteristic single-domain like (SDL) magnetization process appeared in the NPM. Since the SDL magnetization is very similar to the pinning behavior in the Sm_2Co_(17) type sintered magnets, the similarity and/or difference in magnetization processes in both magnets was investigated in this study. The conclusion of this study is the SDL or pinning behavior in the NPM originates from the strong interaction between domain walls and grain boundary regions, and that is the very unique phenomenon in the magnets compared to the typical pinning behavior in the Sm_2Co_(17) type sintered magnets.