The making method of high coercive micro-structured powder for bonded magnets and The magnet powder

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Disclosed is a method of preparing a micro-structured powder for bonded magnets having high coercivity, which is advantageous in terms of low preparation costs by recycling magnet scraps, simplified mass production, minimal environmental contamination by such a recycling process, and the preparation of stable anisotropic powders having high coercivity. Further, a magnet powder prepared by the above method is provided. The current method is characterized in that R-Fe-B type anisotropic sintered magnets or scraps thereof are crushed to prepare 50-500 mum sized magnet powders, which are then mixed with 1-10 wt % of rare earth fluoride (RF3) powders and thermally treated at high temperatures (500-1100° C.) in a vacuum or an inert gas, to cause the change of matrix-near surface and grain boundary of the powders. Thus obtained powders include a matrix phase having R2Fe14B crystal structure, a R-rich grain boundary phase containing rare earth fluoride, and other phases, in which the matrix phase has an average grain size of 1-20 mum, and the powders have an average size of 50-500 mum with superior magnetic characteristics of (BH)max>=20 MGOe and iHc>=5 kOe.