Patent ID: 8075707

Claim:
A method for preparing a rare earth permanent magnet material, comprising a disposing step of disposing a powder on a surface of a sintered magnet body of R 1 a T b A c M d composition wherein R 1 is at least one element selected from rare earth elements inclusive of Sc and Y, T is Fe and/or Co, A is boron (B) and/or carbon (C), 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 d indicative of atom percent based on the alloy are in the range: 10≦a≦15, 3≦c≦15, 0.01≦d≦11, and the balance of b, 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 having an average particle size equal to or less than 100 μm, and then a heat treating step of heat treating the sintered magnet body and the powder at a temperature equal to or below the sintering temperature of the magnet body in vacuum or in an inert gas for absorption treatment for causing at least one of R 2 , R 3 , and R 4 in said powder to be absorbed in said magnet body, a cooling step of cooling the magnet body after the heat treating step; followed by repeating the disposing step, the heat treating step and the cooling step, in the recited order, at least two times.