Rare earth permanent magnet

摘要

A rare earth permanent magnet is in the form of a sintered magnet body having a composition R 1 a R 2 b T c A a F e O f M g wherein F and R 2 are distributed such that their concentration increases on the average from the center toward the surface of the magnet body, the concentration of R 2 /(R 1 +R 2 ) contained in grain boundaries surrounding primary phase grains of (R 1 ,R 2 ) 2 T 14 A tetragonal system within the sintered magnet body is on the average higher than the concentration of R 2 /(R 1 +R 2 ) contained in the primary phase grains, and the oxyfluoride of (R 1 ,R 2 ) is present at grain boundaries in a grain boundary region that extends from the magnet body surface to a depth of at least 20 µm. The invention provides R-Fe-B sintered magnets which exhibit high magnet performance despite minimal amounts of Tb and Dy used.