Method for preparing permanent magnet material

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A permanent magnet material is prepared by machining an anisotropic sintered magnet body having the compositional formula : R x (Fe 1-y Co y ) 100-x-z-a B z M a wherein R is Sc, Y or a rare earth element, M is Al, Cu or the like, to a specific surface area of at least 6 mm -1 , heat treating in a hydrogen gas-containing atmosphere at 600-1, 100°C for inducing disproportionation reaction on the R 2 Fe 14 B compound, and continuing heat treatment at a reduced hydrogen gas partial pressure and 600-1, 100°C for inducing recombination reaction to the R 2 Fe 14 B compound, thereby finely dividing the R 2 Fe 14 B compound phase to a crystal grain size ‰ 1 µm.