Anisotropic local hardening in hot-deformed Nd-Fe-B permanent magnets
Anisotropic local hardening in hot-deformed Nd-Fe-B permanent magnets
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DOI：
10.1016/j.actamat.2017.12.059
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发表时间：
2018-04
期刊：
影响因子：
9.4
通讯作者：
S. Sawatzki;T. Schneider;M. Yi;E. Bruder;S. Ener;M. Schönfeldt;K. Güth;Bai-Xiang Xu;O. Gutfleisch
中科院分区：
文献类型：
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作者：
S. Sawatzki;T. Schneider;M. Yi;E. Bruder;S. Ener;M. Schönfeldt;K. Güth;Bai-Xiang Xu;O. Gutfleisch
低熔点Nd-Cu合金的扩散对于提高热变形Nd-Fe-B永磁体的矫顽力Hc和研究局部硬化机制，特别是富Nd晶界在纳米尺度Nd-Fe-B晶粒磁去耦中的作用是非常有效的。在这项研究中，我们发现，对于一个Nd-Cu扩散平行于织构轴的增加H c是高于垂直于它的扩散，强烈依赖于扩散深度，而剩磁的发展以相反的方式。我们注意到以下三个观察结果来解释这种行为的结果：a）通过能量色散X射线（EDX）图显示的平行扩散的总Nd和Cu浓度较高，导致通过克尔显微镜观察到的相互作用域的宽度的明显变化，B）通过电子背散射衍射（EBSD）观察到的Nd 2 Fe 14 B晶粒的错位程度较高，以及c）在宏观尺度上由偶极和交换相互作用控制的更有效的局部硬化，如通过微磁模拟所建模的。未对准以及Nd和Cu的掺入也导致磁体的体积膨胀约0.6-0.8%，如通过原位热光测量（TOM）所证明的。
The diffusion of low-melting Nd-Cu alloys is very effective to increase coercivity H c in hot-deformed Nd-Fe-B permanent magnets without the use of heavy rare earth and to study the local hardening mechanism, especially the role of the Nd-rich grain boundary on the magnetic decoupling of the Nd-Fe-B grains on the nanoscale. In this study, we found that for a Nd-Cu diffusion parallel to the texture axis the increase in H c is higher than for a diffusion perpendicular to it and strongly depends on the diffusion depth whereas remanence develops in an inverse manner. We note the following three observations to explain This behavior results from: a) a higher overall Nd and Cu concentration for the parallel diffusion revealed by global energy dispersive X-ray (EDX) maps leading to a distinct change in the broadness of the interaction domains visualized by Kerr microscopy, b) a higher degree of misalignment of the Nd 2 Fe 14 B grains observed by electron backscattered diffraction (EBSD), and c) a more effective local hardening on the macroscopic scale governed by dipolar and exchange interactions as modeled by micromagnetic simulations. The misalignment and the incorporation of Nd and Cu also lead to a volume expansion of the magnet of around 0.6–0.8% as proven by in-situ thermo-optical measurements (TOM).