Coercivity enhancement and thermal-stability improvement in the melt-spun NdFeB ribbons by grain boundary diffusion

摘要

Rapidly quenched NdFeB ribbons with high coercivity were obtained by Nd_(70)Cu_(30) diffusion process. Samples with a high coercivity of 22.02 kOe at room temperature were obtained after grain boundary diffusion with 20 wt% Nd_(70)Cu_(30) alloys. The NdCu diffusion process promoted grain growth in the ribbons, and grain boundary phases were formed with Cu segregation among NdFeB grains. Coercivity above 10 kOe at 150 ℃ was achieved in the bonded magnets with NdCu content over 10 wt%. The flux loss of bonded magnets was reduced by ～32% at 120 ℃ after diffusion treatment with only a small amount (2wt%) of NdCu.