Effect of Homogenization and Precipitation Heat Treatments on Localized Corrosion of Al-Mn-Zr Alloy with Fe Impurity

Abstract

This study aimed to enhance the corrosion resistance of an Al-Mn-Zr alloy containing Fe impurities by using heat-treatment processes. Three processes were implemented to distribute intermetallic particles uniformly, promote Al6(Mn, Fe) and Al3Zr particle formation, and eliminate Fe and Zr segregation. Increasing the amount of Al6(Mn, Fe) reduced the galvanic effect between the Al matrix and Al3Fe particles, leading to improved localized corrosion resistance. Al3Zr promoted smaller grain size by preventing recrystallization. Microstructure analysis confirmed the inhibitory effect on grain growth and the promotion of Al6(Mn, Fe) and Al3Zr particle formation. The effect of grain size on galvanic corrosion was evaluated through corrosion simulation. Furthermore, the improved localized corrosion resistance was evaluated through electrochemical and immersion tests. Consequently, the designed heat-treatment process significantly improved the localized corrosion resistance of the Al-Mn-Zr alloy with Fe impurities. These results demonstrate the effectiveness of the used heat-treatment processes in improving the corrosion resistance of the alloy.