METHOD FOR PRODUCING RARE EARTH SINTERED MAGNET AND RARE EARTH SINTERED MAGNET

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PROBLEM TO BE SOLVED : To provide a method for producing a rare earth sintered magnet that uses a small amount of Tb and Dy and is high in heat resistance. SOLUTION : A strip cast alloy is casted, the strip cast alloy having a composition : R1aTbMcAd (R1 is an element or a combination of two or more elements selected from rare earth elements including Sc and Y and contains Nd and/or Pr as essential elements, T is Fe or Fe and Co, M contains Al and Cu as essential elements and is a combination of two or more predetermined elements, A is B or B and C, a-d represent atomic percent in the alloy and are in the range : 12.5≤a≤18, 0.2≤c≤10, and 5≤d≤10, while b is the balance. The strip cast alloy is subjected to HDDR treatment and diffusion treatment at 1, 000°C or below, and a rare earth sintered magnet having an average crystal particle size of 0.2-2 μm is obtained by using microcrystalline alloy powder that comprises microcrystalline particles of an Nd2Fe14B crystal phase having an average crystal particle size of 0.1-1 μm, and an R1-rich grain boundary phase surrounding the microcrystalline particles with an average width of 2-10 nm. COPYRIGHT : (C)2014, JPO&INPIT