RARE EARTH-IRON-BORON BASED MAGNET AND METHOD FOR PRODUCTION THEREOF

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[PROBLEM] To provide a high performance rare earth based magnet, characterized in that it exhibits a high coercive force or a high remanent magnetic flux density even when it has a reduced content of a rare earth element such as Dy, which is scarce. [CONSTITUTION] A rare earth - iron - boron based magnet, characterized in that it has a grain boundary layer being enriched in M element [wherein M represents one or more of rare earth elements selected from among Pr, Dy, Tb and Ho] by the diffusion of the M element from the surface of the magnet, and that a coercive force Hcj and the content of M element in the whole of a magnet satisfies the following formula : Hcj >= 1 + 0.2 X M [wherein 0.05 = 1.68 - 0.17 X Hcj [wherein Br represents a remanent magnetic flux density in the unit of T]. © KIPO & WIPO 2007