(1. 燕山大学 机械与工程学院，秦皇岛 066004；
2. 北京航空材料研究院，北京 100095)
摘 要: 研究室温大气环境下2E12铝合金微观组织与疲劳裂纹扩展行为之间的关系，并分别利用光学显微镜、透射电镜和扫描电镜对合金的微观组织及疲劳断口进行分析。结果表明：合金的疲劳裂纹扩展速率与合金中微米级第二相粒子的体积分数成正比，且随着亚微米级第二相粒子尺寸的增加及晶粒尺寸的减小，合金的疲劳裂纹扩展速率明显降低，尤其是在Pairs区及以后，其值降低30%；在低速扩展区，合金断口呈现脆性的准解理断裂特征，在中速扩展区，合金出现清晰的疲劳条纹。
关键字: 2E12铝合金；疲劳裂纹扩展；晶粒；微米级第二相；亚微米级第二相
（1. School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The interrelationship between microstructure and fatigue crack propagation behaviors of 2E12 aluminum alloys was investigated at room temperature in air. The microstructures and fatigue fracture surfaces of the alloy were examined by optical microscopy, transmission electron microscopy and scanning electron microscopy. The results show that the fatigue crack growth rate is proportional to the volume fraction of micro-sized second-phase particles. And with the increase of submicro-sized second-phase particles size and the decrease of grain size, the fatigue cracks propagate much slowly, reducing by 30% or more at Pairs region. In a low fatigue crack growth rate region, alloy shows quasi-cleavage fracture features. In a middle fatigue crack growth rate region, the fatigue striation features are clear.
Key words: 2E12 aluminum alloy; fatigue crack propagation; grain; micro-sized second-phase particles; submicro-sized second-phase particles
