R-Fe-B-based sintered rare earth 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 part even in an R-Fe-B based rare earth sintered magnet body, to improve coercive force while suppressing degradation of residual magnetic flux density, and to improve corrosive resistance. SOLUTION : This R-Fe-B based rare earth sintered magnet includes : an R-Fe-B based rare earth sintered magnet body having, as a main phase, an R2Fe14B-type compound crystal grain containing a light rare earth element RL (at least kind out of Nd and Pr) as a main rare earth element R; and a protective layer formed on a surface of the R-Fe-B based rare earth sintered magnet body. The R-Fe-B based rare earth sintered magnet body contains a heavy rare earth element RH (at least kind selected from a group consisting of Dy, Ho and Tb). The protective layer contains the light rare earth element RL, and has a part having a thickness ≥0.5 μm. COPYRIGHT : (C)2011, JPO&INPIT