R-Fe-B-based method for manufacturing sintered rare earth magnet

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PROBLEM TO BE SOLVED : To increase a coercive force of an R-Fe-B based rare earth sintered magnet body while preventing the lowering of residual magnetic flux density by efficiently forming main phase crystal grains with heavy rare earth elements RH concentrated in the outer shell even in the inner part of the R-Fe-B based rare earth sintered magnet body.SOLUTION : A method for producing R-Fe-B based rare earth sintered magnet executes : a step (A) which prepares at least one R-Fe-B based rare earth sintered magnet body 1 having RFeB-type compound crystal grains containing a light rare earth element RL as a main rare earth element R; a step (B) which arranges foil 2 containing a heavy rare earth element RH in a treatment chamber together with the R-Fe-B based rare earth sintered magnet body 1 with the foil 2 coming into contact with the R-Fe-B based rare earth sintered magnet body 1; and a step (C) which supplies the heavy rare earth element RH to the surface of the R-Fe-B based rare earth sintered magnet body 1 from the foil 2 by heating the foil 2 and the surface of the R-Fe-B based rare earth sintered magnet body 1 to diffuse the heavy rare earth element RH into the R-Fe-B based rare earth sintered magnet body 1. A plurality of the R-Fe-B based rare earth sintered magnet bodies 1 are arranged so as to hold the foil 2 therebetween.