Abstract A series of sandwiched structures with different near-surface mass fractions x (x = 3 wt%, 4 wt%, 5 wt%) was employed to develop high-coercivity hot-deformed Nd-Fe-B magnets by the addition of 2 wt% Nd-Cu eutectic alloys via adjusting the middle thickness and near-surface thickness. The designed magnet with a pronounced composite structure shows a 23% increase in coercivity with a 6% loss of remanence by adjusting the sandwiched structure at 4 wt% Nd-Cu eutectic alloys in the near-surface regions. The results indicate that the near-surface Nd-Cu-rich “shell” structure can effectively suppress the magnetization reversal of overall magnets, enhancing the coercivity. With the help of loading stress, Nd-Cu liquid enriched at the near-surface regions of the sample is infiltrated into the Nd-Cu-lean middle region, resulting in a concentration gradient. Microstructure characterizations further demonstrate that the infiltrated Nd-Cu eutectic plays a critical role in inhibiting grain growth and intergranular magnetic interaction. The optimized microstructure features suppress the reversed magnetization process, which makes a positive contribution to coercivity.

中文翻译：

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Nd-Cu共晶合金扩散加工热变形Nd-Fe-B永磁体夹层结构

摘要 采用一系列不同近表面质量分数 x (x = 3 wt%, 4 wt%, 5 wt%) 的夹层结构，通过添加 2 wt% Nd-Cu 共晶合金通过调整中间厚度和近表面厚度。通过调整近表面区域中 4 wt% Nd-Cu 共晶合金的夹层结构，具有明显复合结构的设计磁体的矫顽力增加 23%，剩磁损失 6%。结果表明，近表面富Nd-Cu“壳”结构可以有效抑制整体磁体的磁化反转，提高矫顽力。在加载应力的帮助下，在样品近表面区域富集的 Nd-Cu 液体渗入到贫 Nd-Cu 的中间区域，导致浓度梯度。微观结构表征进一步表明，渗透的 Nd-Cu 共晶在抑制晶粒生长和晶间磁相互作用方面起着关键作用。优化的微观结构特征抑制了反向磁化过程，这对矫顽力有积极的贡献。