R-Fe-B BASED RARE EARTH SINTERED MAGNET AND ITS MANUFACTURING METHOD

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PROBLEM TO BE SOLVED : To efficiently form a main phase crystal grain in which heavy rare earth elements RH are concentrated in an outer shell even in an inner of an R-Fe-B based rare earth sintered magnet object, to improve coercive force while deterioration of residual magnetic flux density is controlled, and to improve corrosive resistance. SOLUTION : An R-Fe-B based rare earth sintered magnet is provided with the R-Fe-B based rare earth sintered magnet object having an R2Fe14B-type compound crystal grain comprising a light rare earth element RL (at least one of Nd and Pr) as a main rare earth element R as a main phase and with a protection layer formed on a surface of the R-Fe-B based rare earth sintered magnet object. The R-Fe-B based rare earth sintered magnet object comprises a heavy rare earth element RH (one selected from a group consisting of Dy, Ho and Tb). The protection layer comprises the light rare earth element RL, and it has a part whose thickness is 0.5 μm or above. COPYRIGHT : (C)2008, JPO&INPIT