Method for preparing high-performance NdFeB magnet through grain boundary diffusion Dy-Cu alloy

Abstract

Provided is a method for preparing a high-performance NdFeB magnet through grain boundary diffusion Dy-Cu alloy. Dy-Cu alloy rapid-hardening thin straps or common cast ingots are coarsely broken and directly serve as a surface diffusion source of the NdFeB magnet, a Dy-Cu-rich thin layer is formed on the grain boundary of the NdFeB magnet through diffusion thermal treatment, and therefore the high-coercivity NdFeB magnet can be obtained. According to the method, Dy-Cu alloy ingredients are designed as required, after the Dy-Cu alloy rapid-hardening thin straps are made or the traditional cast ingots are coarsely broken, the Dy-Cu alloy rapid-hardening thin straps or the traditional cast ingots are laid around the NdFeB magnet and heated till the temperature is slightly higher than the temperature of the melting point of the Dy-Cu alloy cast ingots so that the Dy-Cu alloy rapid-hardening thin straps or the traditional cast ingots can be molten to be in a liquid state and attached to the surface of the NdFeB magnet, then annealing thermal treatment is performed, and finally, the product is obtained. The diffusion source Dy-Cu alloy will be molten to be in a liquid state within the grain boundary diffusion thermal treatment temperature range, the Dy-Cu alloy rapid-hardening thin straps or the traditional cast ingots can be coarsely broken and serve as the diffusion source, the process that the Dy-Cu alloy rapid-hardening thin straps or the traditional cast ingots are made into fine powder with which the surface of the NdFeB magnet is coated is omitted, diffusion of Dy elements and Cu elements in the grain boundary can be accelerated, the depth of a diffusion layer is increased, and the high-performance NdFeB magnet can be obtained.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, in particular to a method for preparing a high-performance NdFeB magnet from a grain boundary diffusion Dy-Cu alloy. technical background [0002] The sintered NdFeB alloy is called "magnet king" because of its high remanence, coercive force and maximum energy product, and excellent comprehensive performance. Since its inception, it has been widely used in electronic information, medical equipment, wind power and automobile industries. After decades of development, the magnetic properties of sintered NdFeB-based permanent magnet alloys have been continuously improved, and the remanence Br and maximum energy product (BH)max have approached the limit value, but the actual coercive force of sintered NdFeB is only 30% of the theoretical value. So, improving the coercive force is the key to improving the overall performance of sintered NdFeB magnets. Sintered NdFeB is mainly comp...

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Problems solved by technology

However, these surface attachment processes currently have deficiencies: the attachments are not dense enough, and the attachment layer is prone to defects in the subsequent operation and transfer process; and the efficiency of grain boundary diffusion heat treatment is not high, which is not conducive to the grain boundary diffusion heat treatment of samples larger than 5mm. These two points are obviously not conducive to the popularization and application of grain boundary diffusion technology.

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