Effect of Al Content on Corrosion Properties in Die-Cast AZXW Alloys

This study evaluates the corrosion behavior of high-pressure die-casting AZXW alloys, focusing on the influence of Al content (6, 9, 11, and 13 wt.%). The Al effect on corrosion resistance is characterized by a dual effect. The corrosion rates initially increase as Al content reaches 9 wt.%, which is attributed to a higher fraction of isolated β phases acting as micro-galvanic cathodes. Conversely, further increasing the Al content to 13 wt.% promotes the development of continuous network β phases, which serve as an efficient physical barrier that stops corrosion propagation. Furthermore, the Volta potential difference (VPD) between the α-Mg and β-phase decreases with rising Al concentrations, alleviating galvanic corrosion, further lowering the corrosion rate.