Synergistic Effect of High Strength‐Grain Refinement and Suppression of Al 6 Fe Phase Coarsening in Additively Manufactured Al‐Fe‐Sc‐Zr Alloys via Mg Addition

To meet the demand for high‐performance lightweight heat‐resistant materials in aerospace and automotive applications, a novel Al‐Fe‐Sc‐Zr heat‐resistant aluminum alloy was fabricated by laser powder bed fusion (L‐PBF). The effects of Mg content (1 wt%, 3 wt%, 5 wt%, and 7 wt%) on formability, microstructure, mechanical properties, and thermal stability were systematically investigated in this study. The results show that this alloy system exhibits excellent processability, with all specimens achieving relative densities above 99%. In terms of mechanical performance, the 5 wt% Mg alloy delivered the optimal strength‐ductility synergy, with an ultimate tensile strength of 566 ± 5 MPa, a yield strength of 510 ± 7 MPa, and an elongation of 7.5% ± 0.5%, outperforming most reported Al‐Fe‐Sc‐Zr alloys. Its yield strength at 300°C remained as high as 107 ± 6 MPa. Mechanistic analysis indicates that Mg addition retards the coarsening of the Al 6 Fe phase, thereby enhancing thermal stability. Overall, 5 wt% Mg is identified as the optimal content that balances formability, mechanical properties, and heat resistance, and this finding provides a crucial basis for the compositional design of this alloy when applied as a lightweight, high‐temperature‐resistant structural material.