(Ce,La)含量对高丰度稀土NdFeB磁体热扩渗行为的影响  

Effect of high abundance rare earth additions on the thermal diffusion process of NdFeB

作　　者：孙亚辉 刘治国 孔光明 张亮 李佳璐 裴文利 SUN Yahui;LIU Zhiguo;KONG Guangming;ZHANG Liang;LI Jialu;PEI Wenli(School of Materials Science and Engineering,Northeastern University,Shenyang 110819,Liaoning,China;Naval Aviation University(Qingdao Campus),Qingdao 266041,Shandong,China)

机构地区：[1]东北大学材料科学与工程学院,辽宁沈阳110819 [2]海军航空大学青岛校区,山东青岛266041

出　　处：《金属功能材料》2024年第6期103-109,共7页Metallic Functional Materials

基　　金：国家自然科学基金资助项目(52371179);吉林省重点研发计划(20240302104GX);海军十四五预研(3020402080304)。

摘　　要：利用((La,Ce)_(0.2)(Pr,Nd)_(0.8))Fe_(bal)B和((La,Ce)_(0.5)(Pr,Nd)_(0.5))Fe_(bal)B高丰度永磁体为原材料,分析了不同(Ce,La)含量磁体的重稀土Dy热扩渗效果及热扩渗行为。研究表明:(Ce,La)含量对磁体热扩渗效果有重要影响,随着(Ce,La)含量增加导致热扩渗效果变差。在热扩渗过程中,Dy沿晶界扩渗进磁体,晶界中的Dy元素也会进入主相晶粒,在其边缘形成(Dy,RE)_(2)Fe_(14)B壳层,同时优化了晶界处富RE相的分布,削弱主相晶粒之间的交换耦合作用,提升了矫顽力。高(Ce,La)含量会使磁体氧含量增加,晶界中含有更多的氧化物,热扩渗过程中缺少富稀土相的配合,导致Dy元素扩散通道不通畅,磁体中主相晶粒的富Dy薄壳层分布较差,所以热扩渗效果变差。基于菲克第二定律计算Dy元素扩散系数,(Ce,La)20和(Ce,La)50磁体扩散表层至中心处扩散系数分别为2.37×10^(-8)和5.70×10^(-9)cm^(2)/s,而晶界向晶粒内扩散的扩散系数分别为1.30×10^(-14)和3.92×10^(-14)cm^(2)/s,可见(Ce,La)含量对热扩渗速率具有明显影响。The effect of different(Ce,La)contents for high abundance rare earth permanent magnets on thermal diffusion have been investigated.The samples compositions were((La,Ce)_(0.2)(Pr,Nd)_(0.8))Fe_(bal)B and ((La,Ce)_(0.5)(Pr,Nd)_(0.5))Fe_(bal)B,respectively.The thermal diffusing behaviors of heavy rare earth Dy were discussed.The results showed that the content of(Ce,La)has a significant influence on the thermal diffusion effect.With the increase of(Ce,La)content,the diffusion effect deteriorated.The analysis of the microstructure and element distribution revealed that Dy diffused into the magnet along the grain boundary,and the Dy element in the grain boundary also entered the mainphase grains,forming a(Dy,RE)_(2)Fe_(14)B shell layer at its edge during the thermal diffusion process.At the same time,the distribution of RE-rich phases at the grain boundary was optimized,weakening the exchange coupling between the main phase grains and improving the coercivity.High(Ce,La)content would lead to an increase in the O content of the magnet,resulting in more oxides in the grain boundary.The lack of coordination with rare earth-rich phases leaded to poor diffusion channels for the Dy thermal diffusion,resulting into inferior distribu tion of the thin Dy-rich shell layer in the main phase grain.Therefore,the performance improvement is not significant.Based on Fick’s second law,the diffusion coefficient of Dy element was calculated.It can be indicated that the content of(Ce,La)has a significant effect on the rate of thermal diffusion.The diffusion coefficients from the surface layer to the center of(Ce,La)20and(Ce,La)50magnets were 2.37×10^(-8) and 5.70×10^(-9)cm^(2)/s,respectively.The diffusion coefficients from grain boundaries to the interior of the grains were 1.30×10^(-14) and 3.92×10^(-14)cm^(2)/s,respectively.

关 键 词：高丰度稀土永磁 矫顽力 扩散系数 热扩渗 

分 类 号：TM2[一般工业技术—材料科学与工程]