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 main phase grains consisting of R₂T₁₄B compounds and a grain boundary phase having a higher amount of R than the above described main phase grains, and which satisfies AVE(X)/Y=0.8 to 1.0; and (X/Y)max/(X/Y)min=2.0 to 13.0, wherein X represents (weight ratio of heavy rare earth elements)/(the weight ratio of all rare earth elements) for a given number of the above described main phase grains Y represents (weight ratio of heavy rare earth elements)/(weight ratio of all rare earth elements) for the sintered body as a whole; AVE(X) represents the mean value of X obtained for the given number of main phase grains; (X/Y)min represents the minimum value of (X/Y) obtained for the given number of main phase grains; and (X/Y)max represents the maximum value of (X/Y) obtained for the given number of the main phase grains.