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

Rapidly quenched NdFeB ribbons with high coercivity were obtained by Nd70Cu30 diffusion process. Samples with a high coercivity of 22.02 kOe at room temperature were obtained after grain boundary diffusion with 20 wt% Nd70Cu30 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 degrees C was achieved in the bonded magnets with NdCu content over 10 wt%. The flux loss of bonded magnets was reduced by similar to 32% at 120 degrees C after diffusion treatment with only a small amount (2 wt%) of NdCu. (C) 2017 Elsevier B.V. All rights reserved.