Nd-Fe-B Magnets: The Gradient Change of Microstructures and the Diffusion Principle after Grain Boundary Diffusion Process
Nd-Fe-B Magnets: The Gradient Change of Microstructures and the Diffusion Principle after Grain Boundary Diffusion Process
复制标题
Nd-Fe-B磁体：晶界扩散过程后微观结构的梯度变化和扩散原理
DOI：
10.3390/ma12233881
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发表时间：
2019-12-01
期刊：
影响因子：
3.4
通讯作者：
Yang, Bin
中科院分区：
文献类型：
--
作者：
Lu, Yaojun;Zhong, Shuwei;Yang, Bin
Tb在烧结Nd-Fe-B磁体中的晶界扩散过程可显著提高磁体的矫顽力。但由于不同深度处微观结构的影响，随着扩散深度的增加，合金的矫顽力增量和温度稳定性逐渐降低，在亚表面层（300-1000 μm）处表现出良好的耐蚀性。根据电子探针（EPMA）测试结果和扩散机制，分析了不同浓度梯度下Tb在晶界和晶内的扩散行为，并将扩散分为3个阶段。第一阶段位于磁体表面，形成了较厚的核壳结构和大量的富稀土相。第二阶段位于次表层，形成均匀连续的富稀土相和薄的核壳结构。第三阶段位于磁体内部较深处，且Tb富集仅存在于三角形晶界处。
The diffusion of Tb in sintered Nd-Fe-B magnets by the grain boundary diffusion process can significantly enhance coercivity. However, due to the influence of microstructures at different depths, the coercivity increment and temperature stability gradually decreases with the increase of diffusion depth, and exhibit good corrosion resistance at a sub-surface layer (300–1000 μm). According to the Electron Probe Micro-analyzer (EPMA) test results and the diffusion mechanism, the grain boundary and intragranular diffusion behavior under different Tb concentration gradients were analyzed, and the diffusion was divided into three stages. The first stage is located on the surface of the magnet, which formed a thick core-shell structure and a large number of RE-rich phases. The second stage is located in the sub-surface layer, forming a uniform and continuous RE-rich phase and thin core-shell structure. The third stage is located deeper in the magnet, and the Tb enrichment only existed at the triangular grain boundary.