摘要
研究了室温大气环境下欠时效态和峰时效态7055铝合金的疲劳裂纹扩展行为,并分别利用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,欠时效态合金的疲劳裂纹扩展速率较慢,表现出较大的疲劳裂纹扩展抗力。而峰时效态合金的疲劳裂纹扩展速率较快,疲劳裂纹扩展抗力较小。用位错的平面滑移性和循环滑移可逆性解释了时效对疲劳裂纹扩展速率的影响。欠时效态和峰时效态的疲劳断口均以穿晶为主。在疲劳裂纹的第二扩展阶段,欠时效态合金呈现清晰的疲劳条纹,而峰时效态合金出现二次裂纹,未发现疲劳条纹。
The fatigue crack propagation behaviors of 7055 aluminum alloy in under-aged and peak-aged states at room temperature in air were investigated. The microstruetures and fatigue fracture surfaces of the alloy were examined by transmission electron microscopy and scanning electron microscopy. The results show that the fatigue crack propagation rate of under-aged alloy is lower than that of peak-aged alloy. The effects of aging conditions on the rate of fatigue crack propagation were explained in terms of the slip planarity of dislocations and the cyclic slip, reversibility. The fatigue fractures of under-aged and peak-aged alloy are all transgranular. In under-aged alloy, fatigue striations were observed. In peak-aged alloy, secondly crackles occur and no striations were observed.
出处
《航空材料学报》
EI
CAS
CSCD
2008年第6期23-26,共4页
Journal of Aeronautical Materials
基金
国家重点基础研究发展计划973计划(2005CB23705)
