Effect of Sb Content on the Microstructures and Properties of Al–Cu–Mg Alloys

Aiming to develop high-strength Al–Cu–Mg alloys tailored for aerospace applications, this study investigates the influence of trace Sb addition on the microstructural evolution and mechanical behavior of Al–Cu–Mg alloys. This study employs scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize the effect of trace Sb addition on the microstructure of Al–Cu–Mg alloys. This study further explores property variations through hardness testing, tensile testing, and friction-wear characterization. Results demonstrate that trace Sb incorporation promotes the precipitation of θ' phase (Al2Cu) in Al–Cu–Mg alloys, mediating a synergistic effect on microstructural refinement and mechanical property enhancement. Following solid solution treatment at 500°C for 1 h and subsequent aging treatment at 200°C for 4 h, the θ' phase in the matrix of the Al–4.5Cu–0.6Mg–0.2Sb (wt %) alloy exhibits a uniform distribution with small particle sizes, leading to enhanced alloy properties. The enhancement of the mechanical properties of the alloy is primarily attributed to the Sb element’s ability to facilitate the fine and uniform precipitation of additional θ' phases. After undergoing solution treatment at 500°C for 1 h followed by aging at 200°C for 4 h, the Sb-modified Al–Cu–Mg alloy demonstrates outstanding mechanical properties. Specifically, the alloy achieves a hardness of 128.2 HV, a tensile strength of 410 MPa, a yield strength of 345 MPa, and an elongation of 8.2%.