The diffusion behavior and striking coercivity enhancement by Dip-coating TbH3 powders in sintered NdFeB magnets

Grain boundary diffusion of Tb can improve the microstructural and magnetic properties of NdFeB magnets. In this paper, we investigated diffusion behavior and coercivity enhancement by dip-coating TbH3 powders in sintered NdFeB magnets. The results show that the coercivity increased rapidly from 14.02 kOe to 23.72 kOe after diffusion. Tb atoms diffused to the surface of the magnet and then into the interior, forming a network Tbrich shell around (PrNd)2Fe14B grains. The higher magnetocrystalline anisotropy (PrNd,Tb)2Fe14B phases determine the coercivity enhancement. The Tb diffusion model was build up from coating layer to the magnet. This work may shed light on developing sintered NdFeB magnets with coercivity enhancement by diffusion technology.

Automated summary

Grain boundary diffusion of Tb can improve the microstructural and magnetic properties of NdFeB magnets. The rapid increase in coercivity after diffusion is mainly attributed to the formation of a Tb-rich shell around (PrNd)2Fe14B grains. The diffusion of Tb into the interior of the magnet plays a key role in enhancing coercivity.