R-T-B-based alloy powder and method for producing same, and R-T-B-based sintered magnet and method

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A method is provided for producing an R-T-B based alloy powder. The method includes providing an alloy powder containing 27.5 to 36.0 mass % of R, where R is at least one among the rare-earth elements and always includes at least one of Nd and Pr, 0.85 to 1.05 mass % of B, 0.1 to 2.5 mass % of element M (Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb and/or Bi), and a balance T, where T is Fe or is Fe and Co; and pulverizing the powder by introducing the powder and a pulverization gas in a pulverization chamber. The pulverization includes attrition while circulating the alloy powder with a flow of the pulverization gas in the pulverization chamber. The pulverization gas has a gauge pressure of 0.75 MPa or more, and the residence time is 6 minutes or more.