Enhanced Strength and Grain Refinement of Hot‐Rolled Al–Cu–Mn–Mg Alloy via Ag‐Controlled Precipitation

This study systematically investigates the effects of Ag microalloying on the microstructure evolution and the mechanical properties of hot‐rolled Al–Cu–Mn–Mg alloys. The research employs a multiscale characterization approach combining scanning electron microscopy, transmission electron microscopy, and tensile testing. The Al–Cu–Mn–Mg–XAg ( X = 0.1, 0.3, 0.5 wt%) alloys were fabricated through an integrated process that included composition optimization, hot rolling, solution treatment, and aging treatment. The results show that increasing the Ag content from 0.1 to 0.5 wt% causes a continuousrefinement of the grain structure, reducing the average grain size from 15.3 to 11.3 μm. This higher Ag content also encpurages phase transformation, particularly the formation of Mg–Ag coclusters at phase interfaces, which effectively replaces the conventional θ′ phases with the Ag‐induced Ω phase. Notably, the 0.5 wt% Ag alloy display outstanding mechanical properties, with an ultimate tensile strength of 503.4 MPa, a yield strength (YS) of 454.3 MPa, and an elongation of 13.5%. A quantitative analysis indicates that precipitation strengthening is the main mechanism behind the YS. Specifically, the contribution of the Ω phase to strength rises significantly from 42.3 MPa (0.1 wt% Ag) to 256.5 MPa (0.5 wt% Ag).