HEAT-RESISTANT NEODYMIUM IRON BORON MAGNET AND PREPARATION METHOD THEREFOR

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The present invention provides a neodymium iron boron magnet prepared from a neodymium iron boron raw material powder coated with a modifying powder, the modifying powder comprising a heavy rare earth oxide and/or a heavy rare earth fluoride. In the numerous steps of preparing a magnet, the present invention starts from a magnet powder, and particularly, coats the surface of magnetic powder particles with a heavy rare earth fluoride or oxide, such that diffusion can be simultaneously carried out during subsequent sintering of the magnet, and the heavy rare earth oxide or fluoride powder coated on the surface of the magnetic powder particles replaces part of a light rare earth material during sintering, and the heavy rare earth material is absorbed by the magnet, thereby increasing a coercive force and effectively suppressing a decrease in residual magnetism. The present invention can improve the coercive force of magnets by using only a small amount of a heavy rare earth material, sparing heavy rare earth resources and reducing production costs. Furthermore, the process is simple and the size of magnets is not restricted.