Corrosion of high Zn content Al-Zn-Mg-Cu alloy in 3.5 wt. NaCl solution

摘要

In this paper, the polished specimens of high Zn content Al-Zn-Mg-Cu alloy after various aging treatments were immersed in 3.5 wt.% NaCl for up to 240 mins. The development of corrosion was monitored using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). There are two stages during the corrosion process, the first stage of attack started with localized corrosion of trenching around the Al-Zn-Mg-Cu particles. In the second stage the pitting corrosion appeared at the grain boundaries, and then developed into intergranular corrosion. This phenomenon is related to the potential difference between the matrix and the precipitates.