Abstract We investigated the flow behavior of γ/γʹ-strengthened Co-12Ti and Co-12Ti-4Mo (at.%) alloys at room and elevated temperatures (up to 900°C) by electron microscopy and density functional theory. The Mo-added alloy exhibited an enhanced compressive yield strength and strain hardening behavior as compared to the reference binary alloy. This behavior could be attributed to a ~25% larger γʹ volume fraction and ~7% higher planar fault energies in Co-12Ti-4Mo. Using electron channeling contrast imaging, we observed interrupted slip bands in the Co-12Ti-4Mo alloy deformed to a strain of 6%, which led to enhanced strain hardening, in contrast to extended slip bands along {111} planes in the Co-12Ti alloy. Interrupted slip band formation in Co-12Ti-4Mo could be explained by rapid exhaustion of dislocation sources and a higher energy barrier required to cut the γʹ precipitates. These effects are due to a reduced γ channel width and substantial hardening effect of γʹ-Co3(Ti,Mo) in the ternary alloy as well as due to the large shear modulus difference between γʹ and γ.

中文翻译：

---

Mo对γ/γʹ-强化Co-Ti基合金力学性能的影响

摘要 我们通过电子显微镜和密度泛函理论研究了 γ/γʹ 强化的 Co-12Ti 和 Co-12Ti-4Mo (at.%) 合金在室温和高温（高达 900°C）下的流动行为。与参考二元合金相比，添加 Mo 的合金表现出增强的压缩屈服强度和应变硬化行为。这种行为可归因于 Co-12Ti-4Mo 中约 25% 的 γʹ 体积分数和约 7% 的平面故障能量。使用电子通道对比成像，我们观察到 Co-12Ti-4Mo 合金中的间断滑移带变形为 6%，这导致应变硬化增强，这与 Co-12Ti 中沿 {111} 面的扩展滑移带形成对比合金。Co-12Ti-4Mo 中形成中断的滑移带可以通过位错源的快速耗尽和切割 γʹ 沉淀物所需的更高能垒来解释。这些影响是由于 γ 通道宽度的减小和 γʹ-Co3(Ti,Mo) 在三元合金中的显着硬化效应以及 γʹ 和 γ 之间的大剪切模量差异所致。