PURPOSE: To obtain R-Fe-B alloy powder for producing a sintered permanent magnet by prescribing the particle size distribution of metal powder and heating temp. when alloy powder contg. no residual unreacted starting material is produced from powder of a rare earth element, the metal powder, a powdery B source and a powdery reducing agent.
CONSTITUTION: A mixture contg. powder of oxides of one or more selected from among Y and rare earth elements, e.g. Nd2O3 powder, metal powder such as Fe powder, a powdery B source such as FeB powder and a powdery reducing agent such as metal Ca is heated and a reduction-diffusion reaction is allowed to take place. The resultant reactional product is put in water, disintegrated, separated by filtration and washed to remove residual by-products. The resultant slurry of powder is vacuum-dried to produce alloy powder contg. practically no residual unreacted starting material. At this time, metal powder including ≥65wt.% particles of 40-200μm size is used and the mixture is heated to 1,000-1,200°C. The objective R-Fe-B alloy powder forming a compact having extremely increased strength in a magnetic field is obtd.
ARAO NAOYA
KASE KATSUYA
