Study the impact of secondary phases on the corrosion resistance and mechanical properties of aluminum alloys under simulated harsh marine environment

This study systematically investigated the corrosion behavior and mechanical performance degradation mechanisms of AA1050, AA2024, AA5052, AA6061, and AA7075 aluminum alloys under a simulated harsh marine atmospheric accelerated environment. In AA2024 and AA7075, the secondary phase particles (Fe-rich, Cu-rich, and Mg-rich phases) exhibit higher potential differences, larger sizes, and greater surface area fractions, whereas those in AA1050, AA5052, and AA6061 are characterized by lower potential differences and smaller sizes. For AA1050, AA5052, and AA6061 alloys, corrosion pits primarily propagate in the depth direction, showing a more vertical corrosion trend. In contrast, for AA2024 and AA7075 alloys, the pits tend to expand laterally across the surface. The tensile strength degradation rates for AA1050, AA2024, AA5052, AA6061, and AA7075 are 25 %, 88.7 %, 31.74 %, 32.4 %, and 42.4 %, respectively, while the elongation degradation rates are 12.5 %, 35.3 %, 14.3 %, 26.3 %, and 31.8 %, respectively. Among the alloys, AA2024 experiences the most severe degradation in mechanical properties. The main reason for the mechanical performance degradation of AA2024 is intergranular corrosion caused by Cu-rich and Mg-rich phases, which lead to stress concentration and accelerate crack propagation.