| 简介 |
PROBLEM TO BE SOLVED : To provide an R-T-B-based sintered magnet which is allowed to have a high coercive force.
SOLUTION : A rare earth based permanent magnet is composed of a sintered compact of R-T-B-based composition (where R includes R1 and R2 as requisites; R1 represents at least one element of rare earth elements including Y but except Dy, Tb and Ho; and R2 represents at least one element of Dy, Tb and Ho). The rare earth based permanent magnet has primary-phase grains of 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 following relations are held : αR1βR2, αR1<αR2, and βR2<βR1. The number of primary-phase grains having the core-shell structure accounts for 5% or more in the total number of the primary-phase grains observed on a cross section of the sintered compact.
SELECTED DRAWING : None
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