RARE EARTH BASED PERMANENT MAGNET

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PROBLEM TO BE SOLVED : To provide a rare earth based permanent magnet which can be effectively increased in coercive force when adding a heavy rare earth element. SOLUTION : A sintered compact of R-T-B-based composition includes two kinds of primary-phase grains M1 and M2 which are different from each other in distribution of R concentration. The element R includes, as requisites, R1 and R2 (where R1 represents at least one of rare earth elements including Y but except Dy, Tb and Ho, and R2 represents at least one of Ho, Dy and Tb). The primary-phase grains M1 and M2 have a core-shell structure including a core part and a shell part covering the core part. Supposing that atomic concentrations of R1 and R2 in the core part are αR1 and αR2 respectively, and atomic concentrations of R1 and R2 in the shell part are βR1 and βR2 respectively, the relations : αR1>βR1, αR2αR2 and βR1βR2, αR1βR2 are held in the primary-phase grain M2. SELECTED DRAWING : None COPYRIGHT : (C)2016, JPO&INPIT