RARE EARTH-IRON-BORON BASED MAGNET AND ITS MANUFACTURING METHOD

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PROBLEM TO BE SOLVED : To provide a rare earth permanent magnet of high performance which is capable of obtaining a high coercive force or a high residual magnetic flux density, even when the content of rare earth elements, such as rare Dy or the like, is reduced. SOLUTION : A rare earth-iron-boron system magnet is provided with a grain boundary, in which M element is enriched by the diffusion of the M element (here : M is one kind or more than two kinds of rare earth element selected from Pr, Dy, Tb, and Ho) from the surface of the magnet. The coercive force Hcj and the M elements content which occupies in the whole of the magnet are shown by a formula : Hcj≥1+0.2×M. In this case 0.05≤M≤10, Hcj : coercive force shown by the unit of MA/m and M : M element content (mass%) which occupies in the whole of the magnet. Further, the magnet is shown by a formula : Br≥1.68-0.17×Hcj. In this case Br : a residual magnetic flux density shown by a unit T.