Patent ID: 7883587

Claim:
A method for preparing a rare earth permanent magnet, comprising the steps of: disposing a powder on a surface of a sintered magnet body of R 1 a T b B c M d O e C f N g composition wherein R 1 is at least one element selected from rare earth elements inclusive of Sc and Y, T is at least one element selected from Fe and Co, 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, and “a” to “g” indicative of atomic percent based on the alloy are in the range: 12≦a≦17, 3≦c≦15, 0.01≦d≦11, 0.1≦e≦4, 0.05≦f≦3, 0.01≦g≦1, and the balance of b, and a≧12.5+(e+f+g)×0.67−c×0.11, said powder comprising at least one compound selected from among an oxide of R 2 , a fluoride of R 3 , and an oxyfluoride of R 4 wherein each of R 2 , R 3 , and R 4 is at least one element selected from rare earth elements inclusive of Sc and Y, and heat treating the magnet body having the powder disposed on its surface at a temperature equal to or below the sintering temperature of the magnet body in vacuum or in an inert gas for 1 minute to 100 hours, for causing at least one of R 2 , R 3 and R 4 in the powder to be absorbed in the magnet body.