Given the limited systematic analysis of microstructural deformation mechanisms in high-cycle fatigue, this study investigates the high-cycle fatigue failure of a fourth-generation nickel-based single crystal superalloy across temperatures of 700 °C, 850 °C, and 980 °C. The results indicate that the alloy exhibits optimal performance at 980 °C, followed by 700 °C and then 850 °C. At 700 °C, stacking fault locks and Lomer-Cottrell dislocations were identified, whereas, at 850 °C, elongated stacking fault shearing and typical cross-slip were observed. Notably, at 980 °C, intense dislocation activity was detected, including Kear-Wilsdorf locks, dislocation pile-up, and entanglement. The observed changes in microstructural mechanisms with increasing temperature are attributed to elevated stacking fault energy and critical shear stress, alongside reduced critical stress for various dislocation movements. Furthermore, the types of Lomer-Cottrell dislocation and Kear-Wilsdorf lock were accurately identified. In conclusion, the dominant micro-deformation mechanisms—stacking fault locks, Lomer-Cottrell dislocations, and dislocation hardening behaviors such as Kear-Wilsdorf locks—significantly enhance high-cycle fatigue performance. This research addresses the scarcity of studies on microscopic deformation mechanisms in single crystal high-cycle fatigue and provides valuable insights for optimizing the high-cycle fatigue performance of nickel-based superalloys.

中文翻译：

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镍基单晶高温合金高周疲劳中温度依赖性的微观变形机理和性能增强前景


鉴于对高周疲劳中微观结构变形机制的系统分析有限，本研究研究了第四代镍基单晶高温合金在 700 °C、850 °C 和 980 °C 温度下的高周疲劳失效。 结果表明，该合金在 980 °C 时表现出最佳性能，其次是 700 °C，然后是 850 °C。 在 700 °C 时，确定了堆叠断层锁和 Lomer-Cottrell 位错，而在 850 °C 时，观察到细长的堆叠断层剪切和典型的交叉滑移。值得注意的是，在 980 °C 时，检测到强烈的位错活动，包括 Kear-Wilsdorf 锁、位错堆积和纠缠。观察到的微观结构机制随温度升高的变化归因于堆积断层能量和临界剪切应力的增加，以及各种位错运动的临界应力降低。此外，还准确识别了 Lomer-Cottrell 脱位和 Kear-Wilsdorf 锁的类型。总之，主要的微变形机制——堆叠断层锁、Lomer-Cottrell 位错和位错硬化行为（如 Kear-Wilsdorf 锁）——显着增强了高周疲劳性能。本研究解决了单晶高周疲劳中微观变形机制研究的稀缺问题，为优化镍基高温合金的高周疲劳性能提供了有价值的见解。