Optimization of densification and its effects on 2:17-type Sm-Co high-temperature magnets

Abstract 2:17-type Sm-Co magnets play an irreplaceable role in the realm of high technology cause their stable operating ability at temperature as high as 500 °C. To further investigate the process of densification and its effects on 2:17 Sm-Co magnets, the alloy powder characteristics, cold isostatic pressing and sintering processes were studied systematically. And the differences in the microstructure and high-temperature performance of the magnets before and after optimization were analyzed and discussed. The powders with suitable average particle size and favorable flowability were prepared by jet milling combined with nitrogen-protected ball milling. Then the optimized magnets were obtained by using delayed high-pressure compaction and a slight negative-pressure sintering process. The optimized magnet exhibits higher density up to 8.40 g cm ⁻³ and the high-temperature performance demonstrates a significant enhancement of H _cj and ( BH ) _max at 500 °C increased by 12.3% and 56.5%, respectively. The magnetic properties at room temperature and 500 °C are as follows: H _cj = 42.38 kOe, ( BH ) _max = 24.45 MGOe and H _cj = 8.013 kOe, ( BH ) _max = 9.147 MGOe, respectively. Furthermore, the B – H curve still remains straight.