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 R-T-B-based alloy powder which comprises 27.5 to 36.0% by mass inclusive of R (wherein R comprises at least one rare earth element and R essentially contains Nd and/or Pr), 0.85 to 1.05% by mass inclusive of B (boron), 0.1 to 2.5% by mass inclusive of element M (wherein M represents at least one element selected from the group consisting of Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, Pb and Bi), and a remainder made up by T (wherein T represents Fe or both of Fe and Co), and which contains a powder at a percent ratio of 20% or more, wherein the powder satisfies the requirement represented by the formula : L/d ≤ 5.39 - 1.07(a/b) wherein a/b represents the ratio of the longer diameter (a) to the shorter diameter (b) in a shape produced by two-dimensionally projecting each particle of the powder and L/d represents the ratio of the perimeter (L) of each particle of the powder to the equivalent circle diameter (d) of the particle (the diameter of a circle having the same area as that of the particle).