NEODYMIUM MAGNET AND METHOD FOR MANUFACTURING NEODYMIUM MAGNET BY THREE-DIMENSIONAL GRAIN BOUNDARY DIFFUSION

A neodymium-iron-boron magnet is provided. The neodymium-iron-boron magnet is subject to diffusion and permeation of a heavy rare earth element, the neodymium-iron-boron magnet includes a heavy-rare-earth diffusion region at a surface layer and a core non-diffusion region, and the neodymium-iron-boron magnet has the heavy-rare-earth diffusion region at regions, which have normal directions consistent with three axes of a three-dimensional Cartesian coordinate system, of the surface layer. The present application extends the principle of diffusion from microscopic grains to macroscopic magnets, that is, from the deposition of heavy rare earth on the surface layer of microscopic grains to the deposition of heavy rare earth on the surface of macroscopic magnets, with more than 20% of the core volume not permeated. Diffusion layers of different depths may be obtained by adjusting temperature and time of heat treatment. Through the magnetic hardening of the surface layer of the magnet, the coercive force of the magnet is increased, and the magnet remanence (Br) and the maximum magnetic energy level (BHmax) are very slightly reduced. Moreover, in the three-dimensional directions, independent adjustment can be realized according to different diffusion depths. The producing process is simple, and highly controllable, which is more suitable for industrialized popularization and application.