Impressive Effect of Li Microalloying and Severe Plastic Deformation of Al–Cu–Mg Alloy on Strength and Corrosion Resistance

This study investigated the simultaneous effect of adding lithium and severe plastic deformation on Al–Cu–Mg alloy’s microstructure, mechanical property, and corrosion resistance. The results showed that under the influence of the dynamic recrystallization executed in the thermo-mechanical process, the initial coarse dendritic structure was replaced by the fine and equiaxed structure. Moreover, adding lithium in amounts less than 0.5 wt% did not have a noticeable effect on the grain size of the extruded alloy. In both series of cast and extruded samples, adding lithium caused a slight change in texture parameters. In the extruded samples, the intensity of the {110} texture was slightly reduced, and the {100} and {111} textures were strengthened compared to the cast sample. Increasing the lithium content in the aluminum intensified the relative amount of lithium in the S-Al₂Cu (Li, Mg) precipitate. The formation of fine GPB zones and {100} texture enhancement resulted in high strength and elongation. By increasing lithium up to 0.5 wt% on Al–Cu–Mg alloy, the corrosion potential and current density decreased 67 and 51%, respectively.