The LCF behavior of SU-263 was investigated at various temperatures (1073, 1123, and 1173 K) and strain amplitudes of ± 0.4 to 0.8% at a constant strain rate of 3 × 10-3 s−1. The alloy displayed initial hardening followed by extensive cyclic softening until failure. It is observed that the presence of dislocation networks absorbs mobile dislocation, and the shearing of γ′ precipitates were responsible for cyclic softening at 1073 and 1123 K, whereas dissolution of γ′ precipitate and dislocation annihilation were responsible for cyclic softening at 1173 K. At elevated temperatures, the LCF behavior is significantly influenced by time-dependent processes such as dynamic strain aging (DSA), and oxidation. The occurrence of DSA manifests in the form of serrated plastic flow in stress–strain hysteresis loops, reduced half-life plastic strain amplitude, and increased cyclic work hardening. The alloy exhibits linear behavior in the Coffin-Manson (C-M) plot at 1073 and 1173 K. However, the C-M plot shows bi-linear behavior at 1123 K with the corresponding shift in the deformation mechanism at ± 0.5% strain amplitude. This study focuses on understanding the effects of temperature on fatigue behavior and the associated deformation mechanisms by using characterization techniques, such as scanning and transmission electron microscopy.

中文翻译：

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温度对镍基高温合金 SU-263 疲劳行为和变形机制的影响


在不同温度（1073、1123 和 1173 K）和 ±0.4% 至 0.8% 的应变幅值下，在 3 × 10-3 s-1 的恒定应变速率下研究了 SU-263 的 LCF 行为。合金表现出初始硬化，然后是广泛的循环软化，直到失效。据观察，位错网络的存在吸收了移动位错，γ' 沉淀物的剪切是 1073 和 1123 K 循环软化的原因，而 γ' 沉淀物的溶解和位错湮灭是 1173 K 循环软化的原因。在高温下，LCF 行为会受到动态应变老化 （DSA） 和氧化等时间相关过程的显著影响。DSA 的发生表现为应力-应变磁滞回线中的锯齿状塑性流动、半衰期塑性应变幅值减小和循环加工硬化增加。该合金在 1073 K 和 1173 K 的 Coffin-Manson （C-M） 图中表现出线性行为。然而，C-M 图显示了 1123 K 时的双线性行为，在 0.5% 的应变幅±变形机制也发生了相应的偏移。本研究的重点是通过使用表征技术（如扫描和透射电子显微镜）来了解温度对疲劳行为和相关变形机制的影响。