本项目以航空发动机用600℃高温钛合金为研究对象，拟从温度、加载频率、应力比和低周疲劳损伤对材料超高周疲劳行为影响规律的试验研究入手，对高温条件下材料超高周疲劳裂纹萌生和早期扩展机制、频率效应、模拟服役环境下的超高周疲劳行为进行深入的研究。重点探讨材料在热、高频低幅、低频高幅载荷耦合作用下局部显微组织的累积响应机理和退化规律，揭示显微组织调控对材料高温超高周疲劳性能的影响规律，建立基于显微组织的疲劳裂纹萌生物理模型和裂纹早期扩展的力学模型。为高温钛合金疲劳寿命预测奠定理论基础，并为航空发动机关键零部件的定寿和可靠性分析提供科学依据。

In this project, experiments will be conducted to determine the effects of temperature, load frequency, stress ratio and low cycle fatigue (LCF) damage on very high cycle fatigue (VHCF) behavior of 600℃ high temperature titanium alloy for aeroengine. The mechanism of crack initiation and early growth for VHCF at elevated temperatures, frequency dependence, and VHCF behavior under operating environment will be investigated. The evolution law of local microstructure under the combined action of heating, loading with high frequency but low amplitude, and loading with low frequency but high amplitude will be further studied. In order to reveal the control parameters of VHCF properties, the relationship between cyclic stress and micro damage characteristics will be emphasized. Finally, models for crack initiation and early growth in VHCF regime will be proposed. This study is expected to establish theoretical basis for fatigue life prediction and reliability evaluation of key components for aerongine.