航空Al-Cu-Mg合金剥落腐蚀行为

采用TEM、电化学等分析方法和手段,对在剥落腐蚀溶液中浸泡不同时间的Al-Cu-Mg合金的剥蚀敏感性及电化学阻抗(EIS)进行研究,分析剥落腐蚀的动力学过程.实验结果表明,2524-T4态合金具有良好的耐剥落腐蚀性能,高Cu含量的第二相粒子是影响合金剥蚀行为的主要因素,合金浸泡2d后才可见明显的点蚀,浸泡4d后局部出现剥蚀现象.根据EIS及EIS等效电路的拟合分析合金的剥蚀行为,发现其动力学过程主要由点蚀的诱导形成、点蚀发展及轻微的剥蚀形成三个阶段组成,而腐蚀的界面反应依次经历氧化膜的溶解、表面腐蚀产物的形成、吸附及脱落的一系列过程.

Exfoliation corrosion behavior of Al-Cu-Mg alloys for aerospace applications

The exfoliation corrosion susceptibility and electrochemical impedance spectroscopy (EIS) of Al-Cu-Mg alloys with different corrosive grades were studied to analyze the dynamic process of exfoliation corrosion by TEM and electrochemical. The results show that 2524-T4 aluminum alloy is good in exfoliation corrosion property, Cu-rich particles are the main influence factor of exfoliation corrosion behavior of the alloy, pitting corrosion occurs after 2d and light exfoliation corrosion can be found after 4d. Using EIS and equivalent circuit to analyze the corrosion dynamic process, the corrosion process includes formation of pitting corrosion, development of pitting corrosion, and formation of exfoliation corrosion. The interface reaction in the corrosion process contains dissolution of oxide film, formation, adsorption and exfoliation of surface corrosion products.