Tailoring Strength–Ductility of Cast Al7Si3Cu0.5Mg Alloy by Manipulating Nano Strengthening Phase

The low strength–ductility of cast aluminum alloys is a critical challenge hindering their engineering applications, particularly when the yield strength exceeds 350 MPa, the fracture elongation is only 4 ≈ 5%. In this study, an aging manipulating strategy is designed to achieve increased number density and decreased size of peak‐aged precipitates ( θ ′ and Q″) in high‐strength Al7Si3Cu0.5Mg cast alloy. These manipulated nanoprecipitates improve the strengthening effect and effectively promote homogeneous dislocation distribution during the plastic deformation stage, effectively improving strain hardening and delaying localized failure. The precipitate‐manipulated Al7Si3Cu0.5Mg cast alloy delivers a yield strength of 385 MPa, ultimate tensile strength of 452 MPa, and fracture elongation of 8.1%, achieving almost twofold improvement of ductility while maintaining high strength. This study reveals critical insights into aging‐induced strength–ductility evolution, proposing effective strategies to achieve significant enhancement of ductility in high‐strength cast aluminum alloy.