R-T-B system alloy powder and manufacturing method thereof, R-T-B system sintered magnet and manufacturing method thereof

摘要

R of 27.5% by mass or more and 36.0% by mass or less (R is at least one of rare earth elements and always includes any one of Nd and Pr), 0.85% by mass to 1.05% by mass % B (boron), 0.1% to 2.5% by weight element M (M is Al, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo) , Ag, In, Sn, Hf, Ta, W, Pb, and Bi), the balance T (T is Fe or Fe and Co), and the particles in two dimensions In the projected contour shape, when the ratio is a / b from the major axis a and the minor axis b, and the ratio is L / d from the circumference L and the equivalent circle diameter d (the diameter of a circle having the same area), L 20% or more of powder satisfying the condition of /d≦5.39-1.07 (a / b) is included R-T-B alloy powder.