Mechanical properties and microstructural evolution in Al–Cu–Mg–Ag alloy with a Cu_xMg_x/10 content

In this study, we investigate the effect of Cu_xMg_x/10 (x = 5.0, 5.5, 6.0, 6.8 wt.%) in Al–Cu–Mg-based alloys on the mechanical properties. Of these, the Cu_6.0Mg_0.60 alloy shows the highest mechanical properties of σ_UTS = 532 MPa (σ_y = 504 MPa) and ε = 11.1%. The amount of Cu_xMg_x/10 solutes affects both macroscopic and microscopic microstructures of fabricated alloys. In the macroscopic observation, a higher content of Cu_xMg_x/10 induces the grain size refinement and the formation of large particles in the grain boundaries. For the microscopic investigation using electron microscopies, the formation of θ′ strengthening phase is more accelerated by a higher content of Cu_xMg_x/10 rather than the formation of Ω phase. Furthermore, microscopic structural distortion is significantly induced with a higher content of Cu_xMg_x/10, which affects the tensile properties of the developed alloys.