Method for producing a sintered magnet R a-Fe-a B

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The invention discloses an R-Fe-B type sintered magnet manufacturing method. The method mainly includes the steps that an R-Fe-B type sintered magnet is prepared as a matrix; a heavy rare earth RHX layer comprising at least one of metal dysprosium, dysprosium hydride, terbium and terbium hydride is distributed on the surface of the matrix, and an RLF layer comprising at least one of praseodymium fluoride, neodymium fluoride, praseodymium oxide and neodymium oxide is distributed on the RHX layer; heat treatment is conducted in a diffusion furnace, the heavy rare earth RHX is diffused into the magnet through the surface of the matrix. By arranging the RLF layer with praseodymium fluoride, neodymium fluoride, praseodymium oxide and neodymium oxide coatings outside the heavy rare earth RHX layer of the magnet, on one hand, magnets can be stacked in the diffusion process and the adhesion is prevented; on the other hand, the heavy rare earth RHX layer is protected against oxidation in the diffusion process, the situation that the heavy rare earth RHX layer is oxidized on the surface of the magnet and influences the diffusion effect is affected, besides, volatilization of the R element in the R-Fe-B type magnet matrix can be prevented in the diffusion process, and it is guaranteed that remanence of the magnet hardly reduces.