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PROBLEM TO BE SOLVED : To provide a permanent magnet which is manufactured through such a manner that films of Dy and Tb are formed on the surface of a rare earth-iron-boron-based sintered magnet prescribed in shape, and that Dy and Tb are diffused into a crystalline grain boundary phase and has a coercive force much higher than usual.
SOLUTION : The manufacturing method of a permanent magnet comprises a film forming process of forming, at least, either a Dy film or a Tb film on the surface of a rare earth-iron-boron-based sintered magnet prescribed in shape; a high-temperature thermal treatment process of forming a diffusion layer which is prescribed in film thickness and contains, at least, either Dy or Tb by subjecting the sintered magnet to a thermal treatment carried out in a high-temperature range on the surface of the sintered magnet, and diffusing, at least, either Dy or Tb into the crystalline grain boundary phase of the sintered magnet; and a low-temperature thermal treatment process of subjecting the sintered magnet to a thermal treatment carried out in a low-temperature range, so as to remove a distortion from the sintered magnet.
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