Abstract The distribution of Rhenium (Re) in a Ni-based single-crystal superalloy is studied by sub-angstrom resolution transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). It is found that Re atoms segregate at the tensile stress regions near the interfacial dislocation cores, forming the “Cottrell atmosphere”, and the segregation process is facilitated by dislocation pipe diffusion. In situ TEM and scanning electron microscopy (SEM) straining studies reveal that the Re-decorated dislocation networks along the phase boundaries act as mechanical walls that effectively block dislocation motion and crack propagation. Furthermore, the degree of Re segregation can be regulated by thermal treatment. Theoretical analysis demonstrates that this remarkable alloying effect originated mainly from the interactions between the local composition strain of Re and the dislocation strains, leading to significantly stabilized interfacial dislocation networks. These results provide a new perspective on understanding the origin of the Re effect on mechanical properties in Ni-based superalloys and will be beneficial to both improving creep properties of Ni-based superalloys and designing high-performance Re-free superalloys.

中文翻译：

---

镍基高温合金界面位错网络处的再偏析

摘要 通过亚埃分辨率透射电子显微镜 (TEM) 和能量色散 X 射线光谱 (EDS) 研究了铼 (Re) 在镍基单晶高温合金中的分布。发现Re原子在界面位错核附近的拉应力区偏析，形成“Cottrell气氛”，并且位错管扩散促进了偏析过程。原位 TEM 和扫描电子显微镜 (SEM) 应变研究表明，沿相界重新装饰的位错网络充当机械壁，有效阻止位错运动和裂纹扩展。此外，Re偏析的程度可以通过热处理来调节。理论分析表明，这种显着的合金化效应主要源于 Re 的局部组成应变与位错应变之间的相互作用，导致显着稳定的界面位错网络。这些结果为理解 Re 对 Ni 基高温合金力学性能的影响提供了新的视角，并将有利于提高 Ni 基高温合金的蠕变性能和设计高性能无 Re 高温合金。