R-T-B Based Rare Earth Permanent Magnet and Method for Production Thereof

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An R-T-B system rare earth permanent magnet, which comprises at least main phase grains consisting essentially of R2T14B 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 : [in-line-formulae]AVE(X)/Y=0.8 to 1.0; and[/in-line-formulae] [in-line-formulae](X/Y)max/(X/Y)min=2.0 to 13.0, [/in-line-formulae]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.