(北京航空航天大学 材料科学与工程学院，北京 100191)
摘 要: 对3.5%NaCl溶液中新型含钪Al-Mg-Cu合金的应力腐蚀开裂宏观性能进行测试，并对裂纹尖端的成分与微观形貌进行分析。根据线弹性断裂力学理论，预制疲劳裂纹试样裂纹尖端处于平面应变状态，得到裂纹匀速扩展时的扩展速率、裂纹尖端应力强度因子以及应力腐蚀开裂强度因子的门槛值。扫描电镜及EDS分析表明：应力腐蚀开裂主要是沿晶扩展，预制裂纹与腐蚀介质中的溶解氧生成Al2O3，产生楔入力促使裂纹扩展；裂纹尖端基体主要发生阳极溶解反应，腐蚀产物以氯化铝为主。
关键字: 含钪铝合金；应力腐蚀开裂；强度因子
new Al-Mg-Cu alloy containing Sc
（School of Materials Science and Engineering, Beihang University, Beijing 100191, China）
Abstract:In 3.5% NaCl solution, the stress corrosion cracking properties of a new Al-Mg-Cu alloy containing scandium were examined. The composition and the micro-morphology of the crack tip were analyzed. According to the linear elastic fracture mechanics, the stress field on the crack tip of the pre-fatigue crack specimen is in a state of plane strain. The crack propagation rate as a constant speed, the stress intensity factor on the crack tip and the threshold stress intensity factor for the stress corrosion cracking are obtained. The results of the scanning electron microscopy and the EDS analyses indicate that the intergranular cracking is dominant in the stress corrosion cracking, due to the fact that the Al2O3 is formed with the oxygen dissolved in the corrosion medium around the pre-crack. Anodic dissolution reaction occurs for the matrix around the crack tip, and the corrosion products are mainly aluminum chloride.
Key words: aluminum alloy containing scandium; stress corrosion cracking; intensity factor
