The study investigates the effect of heat treatment on the microstructure evolution and properties of an age-hardened ­Cu-3Ti-2Mg alloy. The precipitated Cu2Mg and β'-Cu4Ti phases consequently yield a depletion of the Cu matrix in regards to Ti and Mg solutes, which enhances the electrical conductivity. The Cu2Mg Laves phase and β'-Cu4Ti phase precipitates increase the hardness of the alloy due to the consistency and coherency of the later phase. However, the decrease of hardness is mainly associated with the coarse microstructures, that can be formed due to the phase transformation from metastable β'-Cu4Ti phase to more stable Cu3Ti phase. In the range of experiments, the optimum process is solution treatment at 700°C for 4 h, with subsequent age-hardening at 450°C for 4 h. The electrical conductivity, hardness, tensile strength, and elongation of the Cu-3Ti-2Mg alloy were 15.34 %IACS, 344 HV, 533 MPa, and 12%, respectively.

A cold roll bonding process is applied to fabricate an AA6061/AA5052/AA6061/AA5052 multi-layer sheet. Two AA6061 and two AA5052 sheets with 2mm thickness are stacked alternately to each other, and reduced to a thickness of 2 mm by multi-pass cold rolling. The roll bonded multi-layer sheet is then hardened by natural aging (T4) and artificial aging (T6) treatments. The as roll-bonded sheet shows a typical deformation structure that the grains are elongated to the rolling direction. However, after T4 and T6 aging treatments, it has a recrystallization structure consisting of the coarse equiaxed grains in both AA5052 and AA6061 sheets. The as rolled material shows a lamella structure in which AA5052 and AA6061 sheets are stacked alternately to each other, having higher hardness in AA5052 than in AA6061. However, T4 and T6 aging treated materials show a different lamella structure in which the hardness of the AA6061 layers is higher than that of the AA5052 layers. The strengths of the T4 and T6 age-treated specimens are found to increase by 1.3 and 1.5 times respectively, compared to that of the starting material.