镍基单晶/柱晶高温合金超高周疲劳研究进展

镍基单晶/柱晶高温合金具有高温强度高、抗氧化性强、抗疲劳性能优异等优点，是目前先进航空发动机涡轮叶片的主要材料。超高周疲劳（疲劳寿命>10⁸）是涡轮叶片在服役中后期面临的主要问题。对镍基单晶/柱晶高温合金的超高周疲劳进行综述，分析结果表明，单晶/柱晶高温合金在高温下存在反常屈服现象；对比不同频率下的疲劳研究，未发现明显的频率效应；分析断裂机理，发现裂纹主要从内部孔洞等铸造缺陷处萌生。总结了疲劳寿命预测模型，展望了镍基单晶/柱晶高温合金超高周疲劳的发展方向。

Very high cycle fatigue of nickel-based single-crystal and directionally solidified superalloys: Review

As the current main material for advanced aero-engine turbine blades, nickel-based single crystal/directionally solidified superalloys have high high-temperature strength, strong oxidation resistance and excellent fatigue resistance. Very-high cycle fatigue (fatigue life>10⁸) is the major problem faced by turbine blades in the middle and late stages of service. This article reviews the very-high cycle fatigue of nickel-based single crystal/directionally solidified superalloys. The analysis results show that single crystal/directionally solidified superalloys have abnormal yielding phenomena at high temperature; comparing fatigue studies at different frequencies finds no obvious frequency effect; analyses of fatigue mechanism find that cracks mainly originate from casting defects such as pores. Finally, the fatigue life prediction model is summarized, and the trends of very high cycle fatigue of nickel-based single-crystal and directionally solidified superalloys are prospected.