Dissecting the Atmospheric Corrosion Mechanisms of Al-Si-Cu Alloys: Effects of Si and Cu Concentrations via Electrochemical and Salt Spray Approaches

The growing need for materials that are both lightweight and resistant to corrosion in sectors such as aerospace, automotive, marine, and defense has led to intensified interest in aluminum alloys. Yet, conventional production methods frequently fall short when it comes to achieving complex shapes and long-lasting performance. This research investigates the corrosion behavior of Al-Si-Cu alloys made by casting under conditions that replicate additive manufacturing. A set of nine ternary alloys containing different proportions of silicon and copper (۵, ۱۰, and ۱۵% by weight) was prepared and examined. Their corrosion performance was evaluated using two complementary approaches: the neutral salt spray test (NSS, following the NM۰۱-۱-۰۰۲ standard) and electrochemical methods, such as potentiodynamic polarization (PPD) and electrochemical impedance spectroscopy (EIS). The electrochemical findings revealed that the AS۵U۵ sample (۵% Si, ۵% Cu) demonstrated the highest corrosion resistance, with a corrosion current density of just ۰.۱۴ µA/cm۲ and a corrosion potential of -۴۱۰ mV/Ag/AgCl. In contrast, the AS۱۰U۱۵ sample showed the highest corrosion rate, reaching ۲۴.۶ µA/cm۲. During the salt spray test, AS۵U۵ also experienced the least surface deterioration after ۷۲ h of exposure. These results highlight a strong link between alloy composition, microstructure, and corrosion performance. This research underscores the strong potential of fine-tuning Al-Si-Cu compositions to improve corrosion resistance, ultimately prolonging the lifespan of structural parts exposed to aggressive environments.

کلیدواژه ها:

Aluminum alloys ، Corrosion Resistance ، Al-Si-Cu ، salt spray test ، potentiodynamic polarization ، Additive Manufacturing