English
Grain boundary diffusion refers to the introduction of a film of heavy rare-earth elements Dy and Tb on the magnet surface, followed by high temperature vacuum diffusion treatment at temperatures above the melting point of the rare-earth-rich phase, resulting in the diffusion of heavy rare-earth atoms along the liquid phase of the grain boundary to the interior of the magnet, forming a (Nd, Dy, Tb)2Fe14B shell layer structure in the epitaxial layer of the main phase grains, enhancing the main phase anisotropy field and making the grain boundary phase continuous and straight, suppressing the magnetic coupling between the main phases, significantly enhancing the Hcj of the magnet while not having much effect on the Br and (BH)max of the magnet.
Based on the classical diffusion theory, by diffusion of a small amount of heavy rare earth into the Intergranular phase, we achieved the goal of obvious increase of coercive force and higher working temperature for magnets.
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