(中国科学院 金属研究所，沈阳 110016)
摘 要: 研究了TC4ELI合金片层组织与短棒α组织中的疲劳裂纹尖端塑性区及裂纹扩展行为。首先通过SEM及TEM观察比较两种显微组织下的疲劳裂纹尖端塑性区，讨论两种显微组织中裂纹尖端塑性区对疲劳裂纹扩展路径及扩展断口的影响，分析裂纹扩展路径和裂纹尖端塑性区对裂纹闭合及裂纹扩展速率的影响。结果表明：与短棒α组织相比，片层组织中具有较大的裂纹尖端塑性区及曲折的裂纹扩展路径，并最终从疲劳裂纹闭合的角度，解释了片层组织具有较低的疲劳裂纹扩展速率的原因。
关键字: TC4ELI合金；裂纹尖端塑性区；裂纹闭合；疲劳裂纹扩展速率
（Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The crack tip plastic zone (CTPZ) and fatigue crack propagation behavior of the lamellar and short-bar microstructures in TC4ELI alloy were studied. CTPZ of the two microstructures were compared by SEM and TEM observations. The influence of CTPZ on the crack propagating style and crack closure level were analyzed in the two microstructures. The results reveal that, compared with the short-bar microstructure, the larger CTPZ and flexuous crack propagating route in the lamellar microstructure induce high crack closure level that will decrease the fatigue crack growth (FCG) rates.
Key words: TC4ELI alloy; crack tip plastic zone; crack closure; fatigue crack growth rate
