Effect of Cu alloying to ZA-24 alloy to corrosion properties in 2.5% NaCl solution

Abstract

Zinc-aluminium alloys (ZA alloys) are widely used in corrosive environments due to their castability and mechanical properties. In this study, ZA-24 and Cu-alloyed ZA-24 alloys were fabricated via gravity casting to investigate the effect of copper addition on corrosion behaviour in 2.5% NaCl solution. Immersion corrosion tests, electrochemical Tafel analysis, SEM-EDS, XRD, and XPS techniques were employed to characterize the corrosion mechanism. The results indicated that Cu addition increased the micro-galvanic corrosion susceptibility, especially enhancing the specific corrosion rate of Al. However, Cu also promoted the formation of a more stable corrosion film, improving long-term corrosion resistance. These findings highlight the dual role of copper in ZA-24 alloys, suggesting design strategies for enhanced corrosion performance.