An insight into the improved microstructure and elevated comprehensive properties of sintered Nd-Fe-B magnets via the infiltration of DyCu alloy
An insight into the improved microstructure and elevated comprehensive properties of sintered Nd-Fe-B magnets via the infiltration of DyCu alloy
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DOI：
10.1016/j.jmrt.2022.08.088
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Y.L. Huang;Q. Rao;Q. Feng;Z. Wu;Y. Yao;Y. Hou;W. Li;J.M. Luo
中科院分区：
文献类型：
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作者：
Y.L. Huang;Q. Rao;Q. Feng;Z. Wu;Y. Yao;Y. Hou;W. Li;J.M. Luo
晶界扩散（GBD）可以最大限度地利用重稀土（HRE）元素，在不降低剩磁和最大磁能积的情况下达到大幅提高矫顽力的目的。本工作基于GBD技术，以Dy30Cu70合金为扩散源制备了高矫顽力Nd-Fe-B磁体。结果表明，随着扩散温度的升高，矫顽力单调增强，从制备态磁体的1103 kA/m增加到900 ℃扩散磁体的1428 kA/m，增加了29.5%，而剩磁略有下降。微观结构表征表明GBD不会改变晶间相的晶体结构。 Dy扩散到基体相中，在基体相的延伸层中形成具有较高磁晶各向异性场的(Nd,Dy)2Fe14B壳层，抑制了反向磁畴的形核。 Cu主要富集在富稀土相中，有助于形成薄层富稀土相，可以有效增加基体相之间的磁隔离效果。因此，晶间相的优化和(Dy,Nd)2Fe14B壳层的形成应该是矫顽力大幅提高的原因。此外，DyCu合金的扩散有利于增强热稳定性和耐腐蚀性。
Grain boundary diffusion (GBD) can maximize the utilization of heavy rare earth (HRE) elements, and achieve the purpose of greatly improving the coercivity without reducing the remanence and maximum magnetic energy product. In this work, based on GBD technique, high coercivity Nd-Fe-B magnets are produced by using Dy30Cu70alloy as the diffusion source. The results show that, with increasing diffusion temperature, the coercivity is enhanced monotonously from 1103 kA/m for as-prepared magnet to 1428 kA/m for diffusion magnet processed at 900 °C, increasing by 29.5%, and the remanence is decreased slightly. Microstructural characterization reveals that the GBD does not change the crystal structure of intergranular phase. Dy has diffused into matrix phase to form the (Nd, Dy)2Fe14B shell with a higher magnetocrystalline anisotropy field in the extended layer of matrix phase, inhibiting the nucleation of reversed magnetic domain. Cu is mainly enriched in RE-rich phase, which is responsible to the formation of thin RE-rich phase and can effectively increase magnetic isolation effect between matrix phases. Thus, the optimization of the intergranular phase and the formation of (Dy, Nd)2Fe14B shell should be responsible to the huge improvement of coercivity. In addition, the diffusion of DyCu alloy is beneficial in enhancing the thermal stability and corrosion resistance.