Owing to the importance of finding better methods and technologies for protecting against corrosion of aluminium alloys, research into the electrochemical characteristics of the corrosion is an ongoing concern. In this paper, the corrosion behaviour of Al–Mg–Si alloys in 3.5 wt% NaCl solution was investigated using multiple methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), potentiodynamic polarisation measurement and electrochemical impedance spectroscopy (EIS). The results suggest that corrosion begins with dealloying of Mg, followed by conversion of MgSi particles into Al–Fe–Mn–Si particles. The corrosion rate increased until it reached a peak and then decreased. The increase in the corrosion rate may be attributed to an increased electrochemical driving force, which is produced by anodic dissolution between the matrix and residual MgSi particles. Additionally, the thin re-deposited layer of inert elements also plays an important role in accelerating the anodic process of the corrosion pit. The passivated corrosion pit and narrowed intergranular corrosion (IGC) pathway cause the area of active dissolution to decrease, thus reducing the corrosion rate.

中文翻译：

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Al-2.1Mg-1.6Si合金在氯化物介质中的腐蚀演变及行为

由于寻找更好的方法和技术来防止铝合金腐蚀的重要性，对腐蚀的电化学特性的研究是一个持续关注的问题。本文采用扫描电子显微镜 (SEM)、透射电子显微镜 (TEM)、动电位极化测量和电化学阻抗谱 (EIS) 等多种方法研究了 Al-Mg-Si 合金在 3.5 wt% NaCl 溶液中的腐蚀行为。 ）。结果表明腐蚀开始于 Mg 的脱合金，然后是 MgSi 颗粒转化为 Al-Fe-Mn-Si 颗粒。腐蚀速率增加直到达到峰值然后下降。腐蚀速率的增加可能归因于电化学驱动力的增加，它是由基体和残留的 MgSi 颗粒之间的阳极溶解产生的。此外，惰性元素的再沉积薄层在加速腐蚀坑的阳极过程中也起着重要作用。钝化的腐蚀坑和变窄的晶间腐蚀（IGC）路径导致活性溶解面积减少，从而降低腐蚀速率。