Rare earth permanent magnetic material and preparation method thereof

Abstract

The invention provides a rare earth permanent magnetic material and a preparation method thereof. The rare earth permanent magnetic material is characterized in that the rare earth permanent magnetic material is formed in the mode that a composite-structure blank composed of a magnetic phase blank and a non-magnetic phase covering the surface of the magnetic phase blank is pressed and sintered and undergoes tempering heat treatment. During preparation, firstly the magnetic phase blank is prepared in a forming stage, then non-magnetic phase mixtures comprising heavy rare earth compounds are applied to the end face of the blank, then sintering and tempering processing are carried out, and in the heat processing process, by means of grain boundary diffusion, a sintered magnet with low heavy rare earth content and high coercivity is obtained. Compared with an existing grain boundary diffusion technique, production efficiency is improved after the technique is adopted. By means of the method, heavy rare earth elements are in grain boundary of gains in the sintered magnet, and accordingly coercivity is improved and meanwhile residual magnetism is reduced to the smallest degree. By means of the method, a large magnet can be prepared, the defect that a large magnet cannot be prepared in a traditional sintered magnet grain boundary diffusion technique is overcome, and preparation and machining cost of the magnet is reduced.

Description

technical field [0001] The invention belongs to the technical field of manufacturing rare earth permanent magnet materials, in particular to a rare earth permanent magnet material with low weight rare earth and high coercive force and a preparation method thereof. Background technique [0002] As an important metal functional material, sintered NdFeB magnets are widely used in many fields such as aerospace and navigation, information electronics, energy, transportation, communication, medical and health care, etc. In many fields, such as electric vehicles, hybrid vehicles and wind power generation, sintered NdFeB magnets are required to have higher coercive force to meet the use requirements at a certain temperature. At present, the commonly used method is to add heavy rare earth element Dy, and Tb partially replaces Nd to improve the coercive force and temperature stability of the alloy. [0003] Unlike light rare earth elements, heavy rare earth elements and transition gr...

AI Technical Summary

Problems solved by technology

[0006] There are obvious shortcomings in the current grain boundary diffusion technology: (1) Due to the limited depth of element diffusion in the grain boundary diffusion technology, heavy rare earth elements cannot diffuse into larger-sized magnets

Therefore, the use of grain boundary diffusion technology is suitable for the preparation of thick sheet magnets (US2010282371, US20080245442), the thickness of the orientation direction can only be controlled within the range of 3.5~10mm, so this technology is not suitable for large magnets

(2) The current heavy rare earth element grain boundary diffusion technology is aimed at the magnet after sintering. Before the diffusion treatment, the magnet needs to be machined. After the diffusion treatment, it needs to be reprocessed due to the change of the magnet size and surface roughness, and the processing cost is high.

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