Effect of Solutionization and Deformation on Microstructural Evolution and Mechanical/Electrical Properties of Al–Mg–Si Alloy with Er + Sc Co‐Addition

Effect of solutionization (two‐step vs one‐step solution treatment) and deformation (one‐step solutionization + deformation vs no deformation) on microstructural evolution and mechanical/electrical properties of an aged Al–Mg–Si alloy with microalloying Er + Sc co‐addition is studied, respectively, in comparison with its counterpart with a single Sc addition at the same total addition content. Experimental results showed that the Er + Sc co‐added Al–Mg–Si alloy displayed a combination of aging hardness and electrical conductivity superior to the single Sc‐added alloy, under either two‐step or one‐step solution treatment. This highlights an effective microalloying way to improve the Al–Mg–Si alloy by partially using cheap Er rather than full addition of expensive Sc. While the introduction of deformation yielded to a higher aging hardness but a lower electrical conductivity in the Er + Sc co‐added alloy apparently than in the single Sc‐added alloy. When comparing among the Er + Sc co‐added alloys, it is found that, although the one‐step solutionization leads to the highest aging hardness (≈102 HV in peak aging) and the deformation introduction results in the highest electrical conductivity (up to 57.3% IACS), the two‐step solutionization brought about the best combination of aging hardness (≈87 HV) and electrical conductivity (up to 56.7% IACS). Microstructural evolution under different treatments is analyzed to rationalize the variation in aging hardness and electrical conductivity especially in the Er + Sc co‐added Al–Mg–Si alloy.