RH DIFFUSION SOURCE, AND METHOD FOR PRODUCING R-T-B-BASED SINTERED MAGNET USING SAME

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Provided is a method for producing an R-T-B-based sintered magnet by diffusing an heavy rare earth element RH from the surface of an R-T-B-based sintered magnet body into the inside of the sintered magnet body with high efficiency. This method for producing an R-T-B-based sintered magnet comprises : a step of preparing an R-T-B-based sintered magnet body (wherein R represents a rare earth element; and T represents a transition metal element mainly comprising Fe); a step of preparing an RH diffusion source that is an alloy comprising 0.2 to 18 mass% inclusive of a light rare earth element RL (which comprises Nd and/or Pr), 40 to 70 mass% inclusive of Fe and a reminder made up by a heavy rare earth element RH (which comprises Dy and/or Tb) wherein the ratio of the heavy rare earth element RH to Fe (i.e., RH : Fe) is 3 : 2 to 3 : 7 by mass; and an RH diffusion step of introducing the R-T-B-based sintered magnet body and the RH diffusion source into a treatment chamber in a relatively movable and approachable or contactable manner to each other and heating the R-T-B-based sintered magnet body and the RH diffusion source at a temperature of 700 to 1000ºC inclusive while moving the R-T-B-based sintered magnet body and the RH diffusion source in the treatment chamber continuously or intermittently.