中文摘要：

研究了Ti-2Al-2.5Zr合金的高温（673K）低周疲行为,结果表明：Ti-2Al-2.5Zr合金的循环变形表现出初始硬化、随后软化和最后二次硬化的特征。在高温和较高应变幅（（Δε_t/2）〉1.0%）条件下,材料的疲劳寿命高于室温下的疲劳寿命。随着应变幅的提高,高温673 K材料疲劳变形后形成的位错组态由位错墙逐渐演变成成熟的位错胞。多系滑移开动和塑性变形均匀性增强是高温Ti-2Al-2.5Zr合金疲劳寿命提高的原因。

英文摘要：

Low-cycle fatigue（LCF） tests of Ti-2Al-2.5Zr samples were performed at 673 K.The cyclic stress response curves show that an initial cyclic hardening followed by cyclic softening was displayed, subsequently second hardening appeared.Furthermore,this alloy displays much higher LCF life at 673 K than that at RT when cyclic strain amplitude（Δε_t/2） exceeds 1.0%.Transmission electron microscopy （TEM） observations revealed that the typical dislocation structures were dislocation wall and cell.The improvement in LCF life of Ti-2Al-2.5Zr can be attributed to homogeneity of plastic deformation due to activation of multiple slips.