Effect of annealing on microstructures and tensile properties of high-pressure torsion-strained low-to-high Fe-content AA5182 aluminum alloys

The sustainable recycling and upcycling of aluminum (Al) scrap, particularly wrought alloys, is imperative in the era of 'green aluminum'. A key challenge is managing iron (Fe) impurity accumulation, which typically degrades mechanical properties. In this study, we present an approach to enhance Fe tolerance in imitated recycled AA5182 Al alloys (0–1.0 wt% Fe) through severe plastic deformation via high-pressure torsion (HPT). We systematically investigated the evolution of microstructures and tensile properties of as-HPTed alloys during annealing at different temperatures. Results demonstrate that HPT effectively fragments and disperses coarse Fe-rich intermetallics. For Fe contents below 0.75 wt%, these fragmented particles resist coarsening and maintain a fine dispersion even after annealing at 325 °C. Further, we reveal that nanoscale Fe-/manganese-rich dispersoids inhibit grain growth via Zener pinning and contribute to strain hardening. These synergistic effects enable the 275°C-annealed AA5182 alloy with 0.3 wt% Fe to achieve a high strength of ∼500 MPa and a uniform plastic strain exceeding 8 %. Our observations highlight the critical role of microstructural engineering via plastic deformation in developing high-performance, Fe-tolerant recycled wrought Al alloys.