Abstract Powder metallurgy (PM) Ni-based superalloys are widely used for aeroengine turbine disc applications due to their excellent mechanical properties and good corrosion resistance at elevated temperatures. Understanding the fatigue crack growth (FCG) mechanisms of PM Ni-based superalloys is important for both disc alloy development and life prediction of disc components in these advanced aeroengines where damage tolerance design prevails. FCG in PM Ni-based superalloys is a complicated function of microstructure, temperature, loading conditions and environment and is usually a consequence of the synergistic effects of fatigue, creep and environmental damage. In this review, the mechanisms controlled by microstructural features including grain size, grain misorientation, γ′ size and distribution on short and long FCG behaviour in PM Ni-based superalloys are discussed. The contribution of creep and environmental damage to FCG has been critically assessed. The competing effects of mechanical damage (i.e. fatigue and creep) and environmental damage at the crack tip are microstructure-sensitive, and usually results in transition between transgranular, mixed-trans-intergranular and intergranular FCG depending on the contribution of environmental damage to FCG processes.

中文翻译：

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粉末冶金镍基高温合金的疲劳裂纹扩展机制——综述

摘要 粉末冶金 (PM) 镍基高温合金由于其优异的机械性能和良好的高温耐腐蚀性能而广泛用于航空发动机涡轮盘应用。了解 PM Ni 基高温合金的疲劳裂纹扩展 (FCG) 机制对于这些先进的航空发动机中的盘合金开发和盘部件的寿命预测都很重要，其中损伤容限设计占优势。PM Ni基高温合金中的FCG是微观结构、温度、加载条件和环境的复杂函数，通常是疲劳、蠕变和环境损伤协同作用的结果。在这篇综述中，微观结构特征控制的机制包括晶粒尺寸、晶粒取向错误、讨论了 PM Ni 基高温合金中短和长 FCG 行为的 γ' 尺寸和分布。蠕变和环境破坏对 FCG 的贡献已经过严格评估。裂纹尖端的机械损伤（即疲劳和蠕变）和环境损伤的竞争效应是微观结构敏感的，通常会导致穿晶、混合跨晶和晶间 FCG 之间的转变，这取决于环境损伤对 FCG 过程的贡献.