Nd-Fe-B系焼結磁石の保磁力発現機構に及ぼす結晶磁気異方性，結晶粒子径，磁区サイズの影響

摘要

Nd-Fe-B系焼結磁石の自動車駆動用モータ部材としての使用量が増加している．他の応用の広がりと相まって，原料資源確保の問題も注目されている．そのような背景から，その基本磁気特性の研究の社会的重要度も増している．特に，同モータ部材としての使用温度が500K付近の比較的高温であることから，同磁石の高保磁力化は重要であり，その関連から保磁力発現棟構の解明が必要である．%The Dy-free and Dy-substituted (0-100%) Nd-Fe-B sintered magnets based on the NEOMAX-50 type magnet were prepared, and the magnetic properties such as the saturation magnetizations, the coercivities and the magnetic anisotropy constants (K_1, K_2) were determined by the obtained data using an high field magnetometer. The domain structures, especially domain widths were measured using MOKE and SEM, and the sizes of magnetic interacted regions were calculated based on the resulted values. The coercivity of the magnets is subjected to, first: the magnetic anisotropy field, second: crystal grain sizes, third: size of group of crystal grains behaving as a cooperated region that reflects the magnetic interaction through the grain boundary (GB).