R—Fe—B sintered magnet and production method therefor

An R—Fe—B base sintered magnet having a composition consisting essentially of 12 to 17 at % of R which is two or more elements selected from rare earth elements inclusive of yttrium and essentially contains Nd, 0.1 to 3 at % of M1 which is at least one element selected from among Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, 0.05 to 0.5 at % of M2 which is at least one element selected from among Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, 4.8+2×m to 5.9+2×m at % of B wherein m is at % of element M2, up to 10 at % of Co, up to 0.5 at % of C, up to 1.5 at % of O, up to 0.5 at % of N, and the balance of Fe, and comprising a main phase containing an intermetallic compound R2(Fe,(Co))14B and a grain boundary phase, wherein

• the grain boundary phase includes an intergranular grain boundary which includes narrow portions each having an intergranular width of up to 10 nm and broad portions each of which is flanked by the narrow portions and has an intergranular width broader than the intergranular width of the narrow portion,
• the broad portion has an intergranular width of at least 30 nm,
• the broad portion has an atomic ratio (Fe/R) of Fe to R of 0.01 to 2.5,
• the main phase contains an HR rich phase of (R′,HR)2(Fe,(Co))14B at its surface portion, wherein R′ is one or more elements selected from rare earth elements inclusive of yttrium and exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is at least one element selected from Dy, Tb and Ho, the HR rich phase having a higher HR content than the HR content of the main phase other than the surface portion.