DyF_(3)热扩渗技术提高NdFeB磁体矫顽力及其机理分析  

Coercivity improvement and its mechanism of NdFeB magnets prepared by thermal diffusion with DyF_(3)

作　　者：旷传方 陈博原 刘富刚 王施正 卢思瑜 裴文利 Kuang Chuanfang;Chen Boyuan;Liu Fugang;Wang Shizheng;Lu Siyu;Pei Wenli(School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学材料科学与工程学院,沈阳110819

出　　处：《材料与冶金学报》2022年第2期128-135,共8页Journal of Materials and Metallurgy

基　　金：国家自然科学基金项目(51871045,52071070);中央高校基本科研业务费(N2017003).

摘　　要：以商业45H磁体为研究对象,用自制的DyF_(3)涂料涂覆到磁体表面,进行热扩渗处理.通过热扩渗温度和时间的正交实验,确定了磁体的最佳热扩渗工艺为940℃×10h,磁体矫顽力从初始的1.39 MA/m提升至1.76 MA/m,增幅高达26.6%.通过对磁体微观组织结构的分析,研究了重稀土元素Dy的热扩渗过程及磁体矫顽力提高机理:随着热扩渗时间的延长,Dy先沿着晶界向磁体内部扩散,同时也会以缓慢的速度从晶界往主相晶粒中扩散,在晶粒表层形成高磁晶各向异性的(Dy,Nd)_(2)Fe_(14)B薄层.合理的热扩渗工艺能优化晶界,使晶界的Dy和富钕相分布连续、均匀,同时主相晶粒表面获得(Dy,Nd)_(2)Fe_(14)B薄层,从而提高磁体的矫顽力。但过长的热扩渗时间会导致晶粒长大和过多的Dy进人晶粒,反而使磁体性能下降.Commercial 45 H magnets were employed as the research object, and homemade DyF_(3) coating was used on the surface of the magnet for thermal diffusion treatment. Through the orthogonal experiment of thermal diffusion temperature and time, the optimal thermal diffusion process was at 940 ℃ for 10 h, and the coercivity of the magnet was increased from 1.39 MA/m to 1.76 MA/m, with an increment of 26.6%. Through the analysis of the microstructure of the magnet, the thermal diffusion process of heavy rare earth element Dy and the mechanism of the coercivity improvement were discussed. With the extension of thermal diffusion time, Dy first diffused into the magnet along the grain boundary. At the same time, Dy also diffused slowly from the grain boundary to the main phase grain, forming a high magnetic anisotropic(Dy, Nd)_(2)Fe_(14)B thin layer on the grain surface. The reasonable thermal diffusion process could optimize the grain boundary, so that the Dy and Nd-rich phases in grain boundary were distributed continuously and uniformly, and the(Dy, Nd)_(2)Fe_(14)B thin layer was obtained on the surface of the main phase grain. Therefore, the coercivity of the magnet was obviously improved. However, over long thermal diffusion time would lead to the grain growth and excess Dy into the grain, which decreased the performance of the magnet.

关 键 词：NDFEB磁体 晶界扩渗工艺 矫顽力 Dy扩渗过程 

分 类 号：TB34[一般工业技术—材料科学与工程]