Patent ID: 8231740

Claim:
A method for preparing a rare earth permanent magnet material, comprising the steps of: disposing a powder on a surface of a sintered magnet body of R 1 —Fe—B composition wherein R 1 is at least one element selected from rare earth elements inclusive of Sc and Y, said powder comprising at least 30% by weight of an alloy of R 2 a T b M c A d H e wherein R 2 is at least one element selected from rare earth elements inclusive of Sc and Y, T is iron or iron and cobalt wherein the content of iron is 30 to 70 atom % based on T, 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 is boron and/or carbon, H is hydrogen, and “a” to “e” is representative of atomic percentages based on the alloy and the range of “a”, “c”, “d” and “e” is 15≦a≦70, 0.1≦c≦10, 0≦d≦12, e=0, and the balance is b, and said powder having an average particle size equal to or less than 100 μm, 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 absorption treatment for causing R 2 and at least one of T, M and A in the powder to be absorbed in the magnet body, and effecting an aging treatment at a lower temperature after the absorption treatment.