LOW-THERMAL-LOAD CONSOLIDATION OF SM-FE-N FLAKE POWDER BY COMBINATION OF CYCLIC COMPRESSION AND CURRENT SINTERING

摘要

Sm-Fe-N alloys, which possess a high magnet performance, are difficult to sinter due to their thermal decomposability. Sm_1Fe_7N magnets were produced from flake powders by cyclic high-pressure compaction and subsequent current sintering with low temperatures. Under the high pressure compression, the flake particles were densely packed while being broken up and orderly stacked. Coarser powder resulted in denser compacts. When the coarse powder of < 355μm was used, it was densified beyond 85% in relative density only by the cyclic compaction with the pressures above 1.2GPa. The compacts were rigidly consolidated by the current sintering in the temperature range of 350～400 °C without the decomposition. Transmission electron microscope (TEM) observation verified interparticle sinter-bonding in the compacts. The developed process finally produced the sintered magnets with the high density up to 93%.