Chemically complex intermetallic alloys (CCIMAs) have emerged as promising materials for achieving exceptional softening resistance at elevated temperatures, owing to their unique superlattice structures and elemental synergism. However, the lack of experimental endeavors and understanding regarding their temperature-dependent mechanical behaviors hinders their advancement for high-temperature applications. Here, we conducted a systematic investigation on the mechanical properties and associated deformation mechanisms of an L1₂-type Co-rich CCIMA using transmission electron microscopy. The Co-rich CCIMA exhibits superior strength across a wide temperature range of 700-900°C, with an anomalous peak yield strength (YS) of ∼1.0 GPa at 700°C, which surpasses most previously reported L1₂-type intermetallic alloys. This superior softening resistance can be primarily attributed to a combination of cross-slip hardening and segregation-assisted hardening. Specifically, massive Kear-Wilsdorf (K-W) locks formed by multiple cube cross-slips of screw dislocations prevail at 700-900°C, providing strong barriers for dislocation movements and enhancing the yield strength (YS) accordingly. More interestingly, we revealed a segregation-assisted formation of superlattice stacking faults and nanotwins at the peak yield temperature (700°C). The interlocking of these substructures and the associated element dragging effect further impeded the propagation of dislocations, contributing to the observed yield anomaly. This work provides in-depth insight into the high-temperature performance and deformation behaviors of CCIMAs, which paves the way for the future development of novel heat-resistant structural alloys.

中文翻译：

---

高温下富钴化学复杂金属间化合物合金的偏析辅助屈服异常


由于其独特的超晶格结构和元素协同作用，化学复杂金属间化合物合金 （CCIMA） 已成为在高温下实现出色软化性的有前途的材料。然而，缺乏实验努力和对其温度依赖性机械行为的理解阻碍了它们在高温应用方面的进步。在这里，我们使用透射电子显微镜对 L1₂ 型富钴 CCIMA 的机械性能和相关变形机制进行了系统研究。富钴 CCIMA 在 700-900°C 的宽温度范围内表现出卓越的强度，在 700°C 时具有 ∼1.0 GPa 的异常峰值屈服强度 （YS），超过了以前报道的大多数 L1₂ 型金属间化合物合金。这种卓越的抗软化性主要归因于交叉滑移硬化和偏析辅助硬化的组合。具体来说，由 screw dislocations 的多个立方体交叉滑动形成的块状 Kear-Wilsdorf （K-W） 锁在 700-900°C 下盛行，为位错运动提供了强大的屏障，并相应地提高了屈服强度 （YS）。更有趣的是，我们揭示了在峰值产率温度 （700°C） 下超晶格堆叠故障和纳米孪晶的偏析辅助形成。这些子结构的互锁和相关的单元拖动效应进一步阻碍了位错的传播，导致了观察到的屈服异常。这项工作为深入了解 CCIMAs 的高温性能和变形行为提供了深入的见解，为新型耐热结构合金的未来发展铺平了道路。