Rare earth permanent magnet

A rare earth permanent magnet in the form of a sintered magnet body having an alloy composition R1aR2bTcAdFeOfMg wherein R1 is at least one element selected from rare earth elements inclusive of Sc and Y and exclusive of Tb and Dy, R2 one or both of Tb and Dy, T is one or both of iron and cobalt, A is one or both of boron and carbon, F is fluorine, O is oxygen, and M is at least one element selected from the group consisting of Al, Cu, Zn, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W, a through g indicative of atom percents of the corresponding elements in the alloy have values in the range:

• 10≦a+b≦15, 3≦d≦15, 0.01≦e≦4,0.04≦f≦4, 0.01 ≦g≦11, the balance being c, said magnet body having a center and a surface,
• wherein constituent elements F and R2 are distributed such that their concentration increases on the average from the center toward the surface of the magnet body, grain boundaries surround primary phase grains of (R1,R2)2T14A tetragonal system within the sintered magnet body, the concentration of R2/(R1+R2) contained in the grain boundaries is on the average higher than the concentration of R2/(R1+R2) contained in the primary phase grains, and an oxyfluoride of (R1,R2) 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.