Coercivity enhancement of Nd-Fe-B sintered magnet by grain boundary diffusion process using Pr-Tb-Cu-Al alloys
Coercivity enhancement of Nd-Fe-B sintered magnet by grain boundary diffusion process using Pr-Tb-Cu-Al alloys
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DOI：
10.1016/j.jmmm.2019.01.062
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发表时间：
2019-05
影响因子：
2.7
通讯作者：
Lu Kechao-;X. Bao;G. Chen;X. Mu;Xuejiao Zhang;X. Lv;Ding Yong;Xuexu Gao
中科院分区：
文献类型：
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作者：
Lu Kechao-;X. Bao;G. Chen;X. Mu;Xuejiao Zhang;X. Lv;Ding Yong;Xuexu Gao
采用Pr70−xTbxCu15Al15(x= 5，10，15，20，原子分数)合金，采用晶界扩散工艺，系统研究了Tb含量和扩散参数(扩散温度和时间)对烧结磁体晶界结构和磁性能的影响。当x从5at%增加到15at%时，扩散磁体的矫顽力从原来的11.9 Koe增加到22.4 Koe(5 at%磁体)和23.5 Koe(15at%磁体)，剩磁略有降低。当掺杂浓度增加到20at%(Ptca-20)时，扩散磁体的矫顽力仅比Ptca-15磁体高0.6 kOe，剩磁急剧下降。因此，应限制Pr-Tb-Cu-Al合金中Tb的含量。当扩散温度和扩散时间从6 0 0 °C和2 h增加到95 0 °C和8 h时，扩散磁体的矫顽力先线性增加，然后趋于稳定。磁性能的增强机制有助于富Tb壳层的磁硬化、连续的富Nd晶界相的磁隔离以及减少富Nd2Fe14B相与Nd2Fe14B之间的晶格失配。此外，通过调整扩散源中Tb的含量和扩散参数，可以优化富Tb壳层沿扩散长度的分布，有助于提高磁体的矫直力。
Effect of Tb content and diffusion parameters (diffusion temperature and time) on boundary structure and magnetic properties of Nd-Fe-B sintered magnet was systematically studied by grain boundary diffusion process (GBDP) using Pr70−xTbxCu15Al15(x= 5, 10, 15, 20, atom fraction) alloys. Whenxincreases from 5 at% to 15 at%, coercivities of diffused magnets increase from the original 11.9 kOe to 22.4 kOe for 5 at% magnet (PTCA-5) and 23.5 kOe for 15 at% magnet (PTCA-15), with a slight decrease in remanence. Withxincreasing to 20 at% (PTCA-20), coercivity of diffused magnet is only 0.6 kOe higher than that of PTCA-15 magnet, with sharp decrease in remanence. So, Tb content in Pr-Tb-Cu-Al alloy should be limited. And when diffusion temperature and time increase from 600 °C and 2 h to 950 °C and 8 h, coercivities of diffused magnet linearly increase first, and then reach stable. The enhancement mechanisms for magnetic properties contribute to magnetic hardening by Tb-rich shells, magnetic isolation by continuous Nd-rich grain boundary phases and reduced lattice misfit between Nd-rich phases and Nd2Fe14B grains. Furthermore, distribution of Tb-rich shells along diffusion length can be optimized by adjusting Tb content in diffusion sources and diffusion parameters, contributing to coercivity enhancement of magnet.