Combined tensile and bending fatigue (CTBF) behavior and failure mechanism of a blade-like specimen, made of a Ni-based alloy DZ125, are experimentally investigated. In order to reveal the geometrical feature and the stress state of the fillet between turbine blade bottom and platform, a blade-like specimen was designed. A novel high temperature experimental methodology was developed to apply the cyclic tensions and high frequency transverse vibration, to the blade-like specimen. CTBF, dwell fatigue (DF) and high stress ratio bending fatigue (BF) tests were performed at 850 °C. Experiment results show that the introduction of high frequency vibration significantly reduced the cyclic life in comparison with DF, while the cyclic tension related dynamic strain aging (DSA) has a positive effect on high cycle fatigue (HCF) life. LCF-related and HCF-related multi-cracks are initiated at the surface due to the effect of bending stress gradient. During CTBF at elevated temperature, LCF, HCF, creep, oxidation, and their interactions contribute to the crack initiation, and linked creep voids, oxidation, and carbide precipitates accelerate the crack growth.

实验研究了由镍基合金 DZ125 制成的叶片状试样的拉伸和弯曲疲劳 (CTBF) 组合行为和失效机制。为了揭示涡轮叶片底部与平台之间圆角的几何特征和应力状态，设计了一个叶片状试样。开发了一种新的高温实验方法，将循环张力和高频横向振动应用于叶片状试样。CTBF、驻留疲劳 (DF) 和高应力比弯曲疲劳 (BF) 测试在 850 °C 下进行。实验结果表明，与DF相比，高频振动的引入显着降低了循环寿命，而循环张力相关的动态应变时效（DSA）对高周疲劳（HCF）寿命有积极影响。由于弯曲应力梯度的影响，LCF 相关和 HCF 相关的多裂纹在表面产生。在高温下的 CTBF 过程中，LCF、HCF、蠕变、氧化及其相互作用促成了裂纹的萌生，而连接的蠕变空隙、氧化和碳化物析出物加速了裂纹的扩展。