Synergistic improvement of strength and conductivity of 6101 alloy with high Fe content modified by trace Sr and Er

This study achieves the synergistic optimization of electrical conductivity and mechanical properties in a high-Fe-content (0.45 wt.%) Al-Mg-Si alloy through Sr-Er composite modification combined with thermo-mechanical processing. Results demonstrate that the addition of Sr and Er significantly alters the morphology of Fe-rich intermetallic compounds in the alloy, promoting the transformation of needle-like β-Fe phase to fishbone-like α-Fe phase, with cold rolling further refining them into uniformly distributed banded structures. The Sr/Er modified alloy exhibits the smallest average equivalent diameter (3.17 μm) and highest distribution density of Fe-rich phase, effectively reducing electron scattering while enhancing dislocation pinning effects. Moreover, the synergistic interaction between Sr-Er modification and thermo-mechanical processing refines grain size and increases precipitate density, thereby strengthening precipitation hardening. After aging treatment at 180°C for 7 h, the Sr/Er modified alloy demonstrates outstanding comprehensive performance, with a yield strength of 216.8 MPa, ultimate tensile strength of 238.1 MPa, elongation of 19.85%, and electrical conductivity of 56.21% IACS. Compared with the unmodified 0.45Fe alloy, both mechanical properties and conductivity are significantly improved. This research provides a feasible strategy to break through the traditional limitation of Fe impurity content (≤0.15 wt.%) in conductive aluminum alloys, establishing a theoretical foundation for the recycling and regenerative applications of high-Fe-content aluminum alloys.