Method for enhancing coercive force of neodymium-iron-boron magnet through evaporation grain boundary diffusion

Abstract

The invention discloses a method for enhancing the coercive force of a neodymium-iron-boron magnet through evaporation grain boundary diffusion, and belongs to the technical field of magnetic materials. The method comprises the specific technical steps that a neodymium-iron-boron orientated compact is subjected to vacuum pre-sintering, and a pre-sintered compact is obtained; rare earth and alloy elements are subjected to evaporation deposition to be in a form of ionized atoms / molecules and are diffused into the neodymium-iron-boron pre-sintered compact through pores of the pre-sintered compact, subsequently, the rare earth and alloy elements are densified through microwave sintering, and grain boundary diffusion is generated, so that the grain boundary structure of the magnet is improved,and the coercive force of sintered neodymium-iron-boron is improved. The method has the advantages that the rare earth and alloy elements as a diffusion source are in the form of gas-phase atoms / molecules, compared with a liquid diffusion source, the elements can more uniformly, effectively and deeply permeate into the magnet, and the periphery of the neodymium-iron-boron main phase is coated withthe elements; through testing, the coercive force of the neodymium-iron-boron magnet product obtained through gas-phase grain boundary diffusion can be increased by 30% or above, the diffusion depthcan reach 6 mm, and the neodymium-iron-boron magnet product has no hydrogen or fluorine generated through liquid-phase diffusion.

Description

technical field [0001] The invention relates to the technical field of magnetic materials, in particular to a method for enhancing the coercive force of an NdFeB magnet by gas-phase grain boundary diffusion. Background technique [0002] High-end applications require sintered NdFeB magnets to have both high remanence Br and high intrinsic coercive force Hcj to improve the anti-demagnetization ability of the magnet under the impact of temperature, vibration and reverse current. Through composition optimization, quick-setting ingot casting, hydrogen explosion, orientation pressing, sintering, cold isostatic pressing, and oxygen control techniques, the remanence of sintered NdFeB magnets is close to the theoretical value. However, the ternary Nd-Fe-B The internal coercive force of the permanent magnet is less than 30% of the theoretical value. The intrinsic coercivity of sintered NdFeB magnets is determined by the phase composition and microstructure of the material, including...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem that the diffusion depth of the existing sintered NdFeB magnet grain boundary is shallow, more diffusion sources remain on the surface of the magnet, and the actual utilization rate of the diffusion source is not high.