Research on Enhancing the Thermal Stability of Heavy Rare Earth-Free Sintered Nd-Fe-B Magnets via Grain Boundary Diffusion AITranslate

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Chinese Library Classification Number:TM273[一般工业技术]

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As a high-quality functional material with superior performance,Nd-Fe-B permanent magnets are widely used in fields such as aerospace,robotics,and renewable energy.However,their poor temperature stability limits their application in high-temperature environments.Currently,grain boundary diffusion using rare earth alloys or compounds has emerged as a promising technique to enhance the permanent magnetic properties of sintered Nd-Fe-B magnets.In this study,cost-effective TbF₃ was introduced into heavy rare earth-free sintered Nd-Fe-B magnets via grain boundary diffusion.The magnetic properties,microstructure,and elemental distribution of the magnets before and after diffusion were investigated.The results show that after TbF₃ grain boundary diffusion,the coercivity of the magnet increases from 16.81 kOe to 23.51 kOe,overcoming the inherent coercivity limitation of heavy rare earth-free sintered Nd-Fe-B.Meanwhile,the temperature coefficient of coercivity of the magnet is significantly improved,and its service temperature range is expanded from 20~100℃to 20~180℃.Electron probe and transmission electron microscopy analyses reveal that numerous Tb-enriched shell structures are formed in the diffused magnets,which effectively hinders the expansion of magnetic domains and enhances the thermal stability of the magnets.This study provides a scalable approach for optimizing the thermal stability of high-performance magnets,while alleviating the cost pressure associated with preparing high-performance Nd-Fe-B magnets via traditional alloy melting methods.