Abstract Elemental segregation to grain boundaries (GBs) can induce structural and chemical transitions at GBs along with significant changes in material properties. The presence of multiple principal elements interacting in high-entropy alloys (HEAs) makes the GB segregation and interfacial phase transformation a rather challenging subject to investigate. Here, we explored the temporal evolution of the chemistry for general high-angle GBs in a typical equiatomic FeMnNiCoCr HEA during aging heat treatment through detailed atom probe tomography (APT) analysis. We found that the five principal elements segregate heterogeneously at the GBs. More specifically, Ni and Mn co-segregate to some regions of the GBs along with the depletion of Fe, Co and Cr, while Cr is enriched in other regions of the GBs where Ni and Mn are depleted. The redistribution of these elements on the GBs follow a periodic characteristic, spinodal-like compositional modulation. The accumulation of elements at the GBs can create local compositions by shifting their state from a solid solution (like in the adjacent bulk region) into a spinodal regime to promote interfacial phase-like transitions as segregation proceeds. These results not only shed light on phase precursor states and the associated nucleation mechanism at GBs in alloy systems with multiple principal elements but also help to guide the microstructure design of advanced HEAs in which formation of embrittling phases at interfaces must be avoided.

中文翻译：

---

偏析驱动的晶界旋节线分解作为高熵合金中相形核的途径

摘要 元素偏析到晶界 (GBs) 会导致晶界处的结构和化学转变以及材料性质的显着变化。高熵合金 (HEAs) 中相互作用的多种主要元素的存在使得 GB 偏析和界面相变成为一个相当具有挑战性的研究课题。在这里，我们通过详细的原子探针断层扫描 (APT) 分析，探索了时效热处理期间典型等原子 FeMnNiCoCr HEA 中一般高角度 GB 的化学随时间演变。我们发现五种主要元素在 GB 处异质分离。更具体地说，Ni和Mn随着Fe、Co和Cr的耗尽而共偏析到GBs的一些区域，而Cr在Ni和Mn耗尽的GBs的其他区域富集。这些元素在 GB 上的重新分布遵循周期性特征、类似旋节线的成分调制。GB 中元素的积累可以通过将它们的状态从固溶体（如在相邻的主体区域中）转变为旋节线状态来产生局部组成，以促进随着分离进行而产生的界面相状转变。这些结果不仅揭示了具有多种主要元素的合金系统中 GB 的相前体状态和相关的成核机制，而且有助于指导必须避免在界面处形成脆化相的高级 HEA 的微观结构设计。GB 中元素的积累可以通过将它们的状态从固溶体（如在相邻的主体区域中）转变为旋节线状态来产生局部组成，以促进随着分离进行而产生的界面相状转变。这些结果不仅揭示了具有多种主要元素的合金系统中 GB 的相前体状态和相关的成核机制，而且有助于指导必须避免在界面处形成脆化相的高级 HEA 的微观结构设计。GB 中元素的积累可以通过将它们的状态从固溶体（如在相邻的主体区域中）转变为旋节线状态来产生局部组成，从而在分离进行时促进界面相状转变。这些结果不仅揭示了具有多种主要元素的合金系统中 GB 的相前体状态和相关的成核机制，而且有助于指导必须避免在界面处形成脆化相的高级 HEA 的微观结构设计。