7A52铝合金电化学局部腐蚀行为  

Electrochemical local corrosion behavior of 7A52 aluminum alloy

作　　者：张平[1] 李奇[2] 赵军军[1] 蔡志海[1] 底月兰[1] 杨臻[1] 

机构地区：[1]装甲兵工程学院装备再制造工程系,北京100072 [2]装甲兵工程学院机械工程系,北京100072

出　　处：《沈阳工业大学学报》2012年第2期154-158,共5页Journal of Shenyang University of Technology

基　　金：国家自然科学基金资助项目(50801066);国防科技重点实验室基金资助项目(9140C8504030809)

摘　　要：为进一步研究7A52铝合金的耐蚀性能和应力腐蚀敏感性,运用电化学方法研究了7A52铝合金在3.5%NaCl溶液中的局部腐蚀行为.用光学显微镜、扫描电子显微镜观察了腐蚀形貌.试验结果表明,Mg2Si首先发生阳极溶解,一些尺寸较小的Mg2Si被完全腐蚀,产生自身的点蚀坑.然后Mg2Si的电位正移与周围基体形成新的腐蚀电偶,其边缘基体作为阳极被腐蚀.被腐蚀的基体形成空穴,Al3+在空穴中聚集并水解,空穴中产生酸性环境.被空穴包围的Mg2Si脱离基体,形成更大的点蚀坑.AlMnFe在整个试验中并未发生腐蚀.In order to further research the corrosion resistance behavior and stress corrosion sensitivity of 7A52 aluminum alloy, the local corrosion behavior of the alloy in 3.5% NaCl solution was studied with the electrochemical method. Both optical microscope and scanning electron microscope were used to observe the corrosion morphology. The experimental results indicate that the anode dissolution of Mg2Si intermetallics occurs firstly. Some Mg2Si intermetallics with smaller size are corroded completely, and thus the spot corrosion pittings are generated. Then the potential of Mg2Si intermetallics moves towards the positive direction and new corrosion couples form. The matrix around the couples is corroded as the anode. The cavities form at the corroded matrix, and the A13~ cations gather in.the cavities and hydrolyze. The acidic environment is generated in the cavities. The Mg2 Si intermetallics surrounded by the cavities are divorced from the matrix, and the bigger spot corrosion pittings form. The A1MnFe intermetallics are not corroded in the whole experiment.

关 键 词：7A52铝合金 电位 电化学 局部腐蚀 第二相 铝锰铁化合物 镁二硅化合物 极化 

分 类 号：TG171[金属学及工艺—金属表面处理]