Coercivity enhancement in sintered Nd-Fe-B magnets by large mass rotating diffusion with Tb strips
Coercivity enhancement in sintered Nd-Fe-B magnets by large mass rotating diffusion with Tb strips
复制标题
DOI：
10.1016/j.jmmm.2020.166682
复制
发表时间：
2020-06
影响因子：
2.7
通讯作者：
Gao Jingyuan;W. Liu;Y. Ming;Q. Wei;B. G. Zhang;L. C. Zhan;S. Jia
中科院分区：
文献类型：
--
作者：
Gao Jingyuan;W. Liu;Y. Ming;Q. Wei;B. G. Zhang;L. C. Zhan;S. Jia
旋转扩散技术特别适用于小尺寸磁铁的批量生产。本文采用2500块小磁体进行大质量旋转扩散，以提高矫顽力。同时，对其性能的均匀性进行了研究。考虑磁性能和良率，在710℃下旋转扩散5 h，再经过940℃5 h和500℃3 h两阶段退火，得到了最优参数，磁体矫顽力可由14.05 kOe提高到23.06 kOe。EPMA结果表明，大部分Tb富集在磁体表面，部分Tb在旋转扩散过程中扩散到晶界相形成磁隔离。经过两段退火处理后，在主相外延层周围形成了许多具有较高各向异性场的（Nd,Tb）2Fe14B取代相，提高了磁体的矫顽力。离散分析和线性拟合表明，这种大规模旋转扩散过程具有良好的均匀性。
Rotating diffusion technology is especially suitable for mass production of small-sized magnets. In this paper, a large mass rotating diffusion with 2500 pieces of small-sized magnets was conducted to enhance coercivity. At the same time, the uniformity of the properties was studied. Taking both magnetic properties and yield rate into account, we obtained the optimal parameters of the rotating diffusion at 710 ℃ for 5 h, following a two-stage annealing process at 940 ℃ for 5 h and at 500 ℃ for 3 h. Thus, the coercivity of the magnet could increase from 14.05 kOe to 23.06 kOe. EPMA results show that most Tb enriches the surface of the magnets, and some Tb is diffused into the grain boundary phase forming magnetic isolation during the rotating diffusion process. After the two-stage annealing process, many (Nd,Tb)2Fe14B substitutional phases with higher anisotropy field are formed around the epitaxial layer of the main phase increasing the coercivity of the magnet. Discrete analysis and a linear fit show excellent uniformity of the properties in this massive rotating diffusion process.