| 摘要 |
PURPOSE:To obtain a particularly dense permanent magnet material excellent in magnetic properties and mechanical properties, by compacting a rare earth-iron group alloy powder in a magnetic field and by subjecting the resulting green compact to two-stage pressure sintering in a pressure sintering furnace under respectively prescribed conditions and then to aging treatment. CONSTITUTION:The rare earth-iron group alloy powder which has a composition consisting of, by atom, 8-30% rare earth elements and the balance one or more elements among Fe, Co, and Ni and containing, if necessary, 2-28% B is compacted in a magnetic field. At this time, it is desirable that the magnetic field to be impressed and the pressurizing force are regulated to >=1KOe and >=0.5t/cm<2>, respectively. Further, the green compact is subjected to primary sintering in vacuum at 900-1,000 deg.C so as to be formed into a primary sintered compact whose density is regulated to >=90% based on the theoretical value. After that, secondary sintering is applied to the above successively in the same furnace under the conditions of 900-1,200 deg.C and 70-150 atm to form a sintered compact having a density as high as >=97% based on the theoretical density. Subsequently, this sintered compact is annealed at a temp., preferably, in a range of 500-800 deg.C to undergo increase of coercive force, so that desired rare earth-iron group sintered permanent magnet material can be obtained. |
