摘要
采用扫描电镜、金相显微和电化学测试等综合评价技术研究7A09铝合金在3.5%NaCl(质量分数)水溶液中的腐蚀和电化学行为。结果表明:7A09铝合金不均一的显微组织结构导致该合金遭受严重的点蚀和晶间腐蚀,其中点蚀主要发生于金属间化合物或其周围,而沿晶界分布的阳极贫铜区的优先溶解是引起晶间腐蚀的主要原因。当不同浸泡时间时,在7A09铝合金表面交替进行着不同钝化膜的生成与溶解过程,并伴随着该合金钝化与去钝化行为的发生。同时,对该合金的腐蚀过程及机制进行分析。
The corrosion and electrochemical behaviors of 7A09 Al？Zn？Mg？Cu alloy were investigated in 3.5% NaCl （mass fraction） solution using complementary techniques such as scanning electron microscopy （SEM）, metallographic microscopy and electrochemical measurements. The results show that both pitting corrosion from or around the intermetallic particles and intergranular corrosion are observed after the immersion test due to the inhomogeneous nature of the microstructure of the 7A09 alloy. The preferential dissolution of the anodic Cu-depleted zone along grain boundaries is believed to be the possible cause of intergranular corrosion. The passivation and depassivation of this alloy show significant dependence of immersion time, owing to the formation and dissolution of various passive films on the sample surfaces. Furthermore, the corrosion process and corrosion mechanism were also analyzed.
基金
Project(JSJC2013209B057)supported by the National Defense Technology Foundation of China
