发表机构
Columbia University; Inner Mongolia University of Science and Technology; New York University（哥伦比亚大学; 内蒙古科技大学; 纽约大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
Al-Zn合金晶界扩散通过改善晶界解耦、形成高各向异性壳层和晶界平滑，显著提升烧结NdFeB磁体的矫顽力。
AI 中文摘要
本研究系统地研究了Al-Zn晶界扩散（GBD）处理对烧结Nd-Fe-B磁体的影响，使用Al₈₀Zn₂₀合金板作为扩散源。合金板被放置在圆柱形样品两端，并在真空（≤5×10⁻³Pa）条件下在900°C和700°C下进行7小时的扩散退火，随后在500°C下进行2小时的回火处理。磁性测量显示，未处理样品的矫顽力为951.5kA/m，经过900°C处理后增加到1158.2kA/m（增加206.7kA/m，21.7%），而700°C处理后为1039.6kA/m（增加88.1kA/m，9.3%），而剩磁从1282mT略微下降到1256mT。扫描电子显微镜（SEM）、能谱仪（EDS）和X射线衍射仪（XRD）分析显示，900°C处理产生更薄、更连续的晶界相和主相晶粒周围的明显核壳结构。EDS映射显示，Al优先富集在Nd₂Fe₁₄B晶粒的壳层区域，而Zn主要分布在晶界相中，其中它降低了晶界相的熔点并提高了其流动性。XRD证实没有形成二次相，尽管略有晶格膨胀表明主相中部分Al取代了Fe。通过计算分析证实，矫顽力的增强归因于三个协同因素：改善的晶界解耦、形成高各向异性壳层层以加强畴壁钉扎、以及晶界平滑以抑制反向畴核生成。总体而言，900°C处理比700°C更有效，为在高温应用中提高烧结Nd-Fe-B磁体的矫顽力提供了一条非重稀土途径。
英文摘要
This study investigates Al-Zn grain boundary diffusion (GBD) treatment on sintered Nd-Fe-B magnets using $Al_{80}Zn_{20}$ alloy sheets as the diffusion source. The alloy sheets were placed at both ends of cylindrical samples and diffusion-annealed at 900$^\circ$C and 700$^\circ$C for 7 hours under vacuum ($\leq5\times10^{-3}$ Pa), followed by tempering at 500$^\circ$C for 2 hours. Magnetic measurements show that coercivity increases from 951.5kA/m in the untreated sample to 1158.2kA/m at 900$^\circ$C (a gain of 206.7kA/m, 21.7\%) and to 1039.6kA/m at 700$^\circ$C (a gain of 88.1kA/m, 9.3\%), while remanence declines modestly from 1282mT to 1256mT after the high-temperature treatment. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD) analyses reveal that the 900$^\circ$C treatment produces a thinner, more continuous grain boundary phase and a distinct core-shell structure around the main-phase grains. EDS mapping shows that Al preferentially enriches the shell region of the $Nd_2Fe_{14}B$ grains, while Zn predominantly resides in the grain boundary phase, where it lowers the melting point of the intergranular phase and improves its fluidity. XRD shows no detectable secondary phases, while the combined XRD, EDS results, and lattice expansion are consistent with possible limited Al incorporation into the main-phase lattice. Verified by computational analysis, the coercivity enhancement is attributed to three synergistic factors: improved grain boundary decoupling, the formation of a high-anisotropy shell layer that strengthens domain-wall pinning, and the smoothing of grain edges to suppress reverse-domain nucleation.
