Crystal boundary diffusion method for improving coercive force and thermal stability of neodymium-iron-boron magnet

Abstract

The invention discloses a crystal boundary diffusion method for improving the coercive force and the thermal stability of a neodymium-iron-boron magnet, and belongs to the field of rare earth permanent magnet materials. According to the method, a quaternary alloy Dy-Ni-Al-Cu with a low melting point is used as a diffusion source and melted and prepared into a rapid-hardening strip, after coarse breaking, the strip casting is laid around the neodymium-iron-boron magnet, and by the adoption of a heat treatment method, the rapid-hardening strip diffuses and enters the magnet along the crystal boundary. After the processing, the coercive force of the magnet is significantly improved, and the magnetic energy product is improved to a certain extent; meanwhile, since the temperature of the diffusion treatment is low, energy consumption can be reduced, the cost can be lowered, and Nd2Fe14B crystal grains can be prevented from growing up; compared with a coating and magnetron sputtering method, the crystal boundary diffusion method omits a powder preparing and coating process in a coating technology and a thin film preparing process in a magnetron sputtering technology. After the technology processing of the crystal boundary diffusion method, the neodymium-iron-boron magnet with the high coercive force and the high thermal stability is finally obtained.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, and in particular relates to a grain boundary diffusion method for improving the coercive force and thermal stability of an NdFeB magnet. [0002] technical background [0003] Sintered NdFeB magnets are widely used in aerospace, information communication, transportation, medical care, energy and other fields because of their excellent magnetic properties. With the rapid development of industries such as hybrid vehicles and wind power, the high temperature of NdFeB magnets Magnetic properties put forward higher requirements, especially coercive force at high temperature. The traditional method to improve the coercive force of NdFeB magnets is to directly add heavy rare earth elements Dy during the smelting process, but the direct addition of heavy rare earth elements makes Dy elements exist in the entire 2:14:1 main phase particles, and the demand for Dy elements Relatively la...

AI Technical Summary

Problems solved by technology

Heavy rare earth elements can be effectively distributed around the grain boundaries after treatment by magnetron sputtering, which significantly improves the coercive force of the magnet, but this method has disadvantages such as low production efficiency, high cost, difficulty in mass production, and large investment in equipment.

There are many domestic and foreign literature reports on the use of Dy fluoride and oxide coating on the surface of the magnet for the study of grain boundary diffusion, which greatly improves the coercive force, but the magnet treated by this method needs to be processed at a high temperature (850-1000 ℃) to diffuse, easily lead to Nd 2 Fe 14 B grain growth

At the same time, the process of surface coating and sticking has problems such as the attachment is not dense enough, and it is easy to fall off in subsequent operations.

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