Patent ID: 7090730

Claim:
An R—Fe—B base sintered magnet of a composition consisting essentially of, in atom percent, 12 to 17% of R which stands for at least two of yttrium and rare earth elements and essentially contains Nd and Pr, 0.1 to 3% of Si, 5 to 5.9% of B, up to 10% of Co, and the balance of Fe, containing a primary phase of R 2 (Fe,(Co),Si) 14 B intermetallic compound, and having a coercive force iHc of at least 10 kOe, characterized in that the magnet is free of a B-rich phase and contains at least 1% by volume based on the entire magnet of an R—Fe(Co)—Si grain boundary phase consisting essentially of, in atom percent, 25 to 35% of R, 2 to 8% of Si, up to 8% of Co, and the balance of Fe.