The aim of the present research is to manipulate the amenability between composition-microstructure-property relationships in two kinds of Al-4Cu-xMg-0.3Ag alloys (where x = 0.4 and 1.4) having different Cu/Mg ratios (~9.54 and ~2.87). The effect of artificial ageing (T6) on the precipitation hardening behavior and resulting mechanical properties were also assessed and compared to two different scenarios of composition. Experimental results revealed that the modification in Magnesium concentration from 0.4 to 1.4 wt.% has a marked effect in increasing the micro hardness, ultimate tensile stress, and elongation of the alloy. Based on the microstructural analysis, the enhancement in mechanical properties was explained and addressed by considering the dual role of Mg content in the base alloy. On one hand, a large size of Mg atom produces a solid solution hardening effect, while on the other hand, a high content of Mg further promotes the formation of second phase S-type precipitate (Al₂CuMg) with various mixed morphologies. This unraveling co-precipitation phases within the matrix provide an obstacle for the dislocation glide thereby increasing mechanical strength and strain hardenability.

The present study aimed to investigate the influence of magnesium (Mg) on the mechanical properties and corrosion behavior of wrought Al–4Cu–xMg–0.6Ag alloys. The results from Optical Microscope, SEM, XRD analysis, and Thermo-Calc simulation were used to identify the microstructure formed after the aging process. Testing for hardness and tensile strength was conducted, in addition to corrosion testing. It was found that Mg significantly impacts the hardness of the alloys, with a high Mg content (low Cu/Mg ratio) increasing the hardness but reducing the tensile strength and ductility. This study attributed this to the formation of the S phase, which is dependent on both the quantity in the bulk and the size of the phase. The grain size was found to be finer with a higher Mg content, since the particle size inhibits grain growth during the artificial aging process. Counterintuitively, the corrosion activity was reduced in the high-Mg-content alloy due to its large particle size and the reduced galvanic cell effect. This study highlighted the importance of considering the effects of Mg on the mechanical properties and corrosion behavior of Al–Cu–Mg–Ag alloys.

This study investigates the effect of cold working on the aging response and mechanical properties of an Al–4Cu–1.4Mg–0.6Ag (wt %) alloy. The alloy was produced from pure elemental constituents and processed by casting, homogenization, hot rolling, and solution heat treatment. Following solution treatment, approximately 11% cold rolling was applied prior to artificial aging to produce a predeformed condition, while an undeformed condition was retained for comparison. The aging behavior of both conditions was evaluated as a function of aging time. Microstructural characterization was performed using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). Cold working pronounced the deformation-induced dislocation density and promoted refinement of the second-phase precipitates. EBSD analysis revealed an increase in KAM-derived GND density in the predeformed condition, while SEM observations showed a finer precipitate distribution after aging. XRD analysis confirmed the formation and evolution of Al–Cu-rich and Al–Cu–Mg-containing secondary phases after the aging process. These findings highlight the role of the retained dislocation structure in stimulating heterogeneous precipitate nucleation and regulating precipitate refinement during aging. Finally, the predeformed condition exhibited a significant enhancement in mechanical properties after aging, with the yield strength increasing from 362 to 470 MPa and the ultimate tensile strength from 391 to 503 MPa, while the elongation increased from 2% to 5%. The improved mechanical response is associated with the dual effect of the deformation-induced dislocation structure and precipitate refinement during aging.