| 简介 |
PROBLEM TO BE SOLVED : To provide a rare earth permanent magnet having such a gradient function as the coercive force at the surface layer of magnet body is larger than the internal coercive force, and in which thermal resistance is enhanced efficiently.
SOLUTION : In a sintered magnet body having R1aR2bTcAdFeOfMg composition, concentration of R2/(R1+R2) contained in the grain boundary is higher in average than that in the main phase crystal grains at the grain boundary surrounding the main phase crystal grains consisting of tetragonal (R1, R2)2T14A in the sintered magnet body, R2 is distributed such that the concentration of component increases in average from the center toward the surface of the magnet body, an acid fluoride of (R1, R2) exists down to a depth region of at least 20 μm from the surface of the magnet body in the grain boundary, and coercive force at the surface layer of the magnet body is higher than the internal coercive force.
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