Patent ID: 7618497
Filing Date: 2009-11-17
Classification: C22C,H01F

Abstract:
1. An R-T-B rare earth permanent magnet, which comprises a sintered body comprising at least: main phase grains comprising R 2 T 14 B compounds (wherein R represents one or more rare earth elements, providing that the term “rare earth element” include Y (yttrium), and T represents one or more transition metal elements essentially containing Fe, or Fe and Co); and a grain boundary phase having a higher amount of R than said main phase grains, which is characterized in that said sintered body satisfies the following formulas: wherein X represents (the amount of heavy rare earth elements) (wt %)/(the amount of all the rare earth elements (wt %)) for a given number of said main phase grains in said sintered body; Y represents (the amount of heavy rare earth elements(wt %))/(the amount of all the rare earth elements (wt %)) for said sintered body as a whole; AVE(X) represents the mean value of X obtained for the given number of said main phase grains; (X/Y)min represents the minimum value of (X/Y) obtained for the given number of said main phase grains; and (X/Y) max represents the maximum value of (X/Y) obtained for the given number of said main phase grains.