R-T-B BASED RARE EARTH PERMANENT MAGNET AND METHOD FOR PRODUCTION THEREOF

摘要

An R-T-B system rare earth permanent magnet, which comprises at least main phase grains consisting essentially of R 2 T 14 B compounds and a grain boundary phase having a higher amount of R than the above described main phase grains, and
which satisfies the following formulas: AVE ( X ) / Y = 0.8 €‰ to €‰ 1.0 ;
and ( X / Y ) max / ( X / Y ) min = 2.0 €‰ to €‰ 13.0 ,
wherein X represents (the weight ratio of heavy rare earth elements) / (the weight ratio of all the rare earth elements) for a given number of the above described main phase grains in the above described sintered body;
Y represents (the weight ratio of heavy rare earth elements) / (the weight ratio of all the rare earth elements) for the sintered body as a whole;
AVE(X) represents the mean value of X obtained for the given number of the main phase grains;
(X/Y) min represents the minimum value of (X/Y) obtained for the given number of the main phase grains; and
(X/Y)max represents the maximum value of (X/Y) obtained for the given number of the main phase grains.