PROCESS FOR PRODUCTION OF NdFeB SINTERED MAGNET AND NdFeB SINTERED MAGNET

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PROBLEM TO BE SOLVED : To provide a process for the production of an NdFeB sintered magnet which have higher coercive force and higher rectangularity of magnetization curve than those of conventional magnet. SOLUTION : The process for the production of the NdFeB sintered magnet which comprises forming a layer containing Dy and/or Tb on the surface of an NdFeB sintered magnet base and heating the obtained magnet precursor to a temperature not exceeding the sintering temperature of the magnet base to diffuse the Dy and/or Tb contained in the layer to the inside of the magnet base through grain boundaries of the base for grain boundary diffusion treatment, characterized in that : (a) the content of metallic rare earth elements in the magnet base is 12.7 at.% or above, (b) the layer is a powder layer formed by the accumulation of a powder, and (c) the powder layer contains metallic Dy and/or Tb in an amount of 50 mass% or above. COPYRIGHT : (C)2009, JPO&INPIT