Effects of grain boundary diffusion process on magnetic properties enhancement and microstructure evolution of hot-deformed Nd-Fe-B magnets  

作　　者：Jiayi He Yukun Liu Zhigao Yu Jiali Cao Hongya Yu Zhongwu Liu 

机构地区：[1]School of Materials Science and Engineering,South China University of Technology,Guangzhou 510640,China

出　　处：《Journal of Rare Earths》2023年第5期698-704,I0003,共8页稀土学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(U21A2052,51774146)。

摘　　要：Grain boundary diffusion(GBD)process is an important approach for producing Nd-Fe-B magnets with high coercivity and high thermal stability.The GBD for hot-deformed Nd-Fe-B magnets with nanocrystalline micro structure is more complicated compared to sintered magnets.Here,we investigated the effects of different GBD methods,i.e.,intergranular addition(in-situ GBD 1#),in-situ GBD from magnet surface during hot pressing and hot deformation(in-situ GBD 2#),and conventional GBD,on the magnetic properties and microstructure of hot deformed magnets.After the treatment by these three GBD approaches using 2 wt%Pr_(40)Tb_(30)Cu_(30)diffusion source,the coercivity of the hot-deformed magnet increases from 1281 to 1567,1412 and 2022 kA/m,respectively.The coercivity enhancement is attributed to the formation of local(Nd,Tb)2Fe14B phase with stro ng magnetic anisotropy.Reduced grain orientation is found in both in-situ GBD 1#and conventional GBD treated samples mainly due to the local stress state variation and the rotation of platelet grains.Interestingly,the in-situ GBD 2#processed sample has a high orientation at diffusion surface,which may be caused by the modified surface state of the magnet by the diffusion source.Compared with the in-situ GBD processes,the conventional GBD exhibits a higher utilization efficiency of Tb.Since the in-situ GBD is effective to treat thick hot-deformed magnets,further effort should be aimed at enhancing its diffusion efficiency.

关 键 词：ND-FE-B Grain boundary diffusion COERCIVITY hot deformation Crystal orientatio 

分 类 号：TM273[一般工业技术—材料科学与工程]