Nickel alloying 7075 aluminum alloy exhibits superior thermal cracking resistance. In order to explore the heat treatment regulation technology of the as-cast alloys

the influence of heat treatment conditions on the microstructure and mechanical properties of the 7075 alloys were investigated comparatively. The results reveal that the solidification microstructure of the alloys is mainly composed of primary α-Al phase and intergranular multi-phase divorced eutectic microstructure. The intergranular Al-Cu-Mg intermetallic compounds are completely dissolved into the matrix alloy after solid solution aging

where the coarse Al

3

Ni intermetallic compound in the as-cast specimens is also refined with dispersed distribution. After heat treatment

the comprehensive mechanical properties of the specimens are significantly improved

where the average tensile strength of 7075 aluminum alloy with 0.6% Ni content is 14% and 17%

higher than that of 7075 alloy and 7075 aluminum alloy with 1.2% Ni content

respectively

indicating that the microstructural control of intergranular compounds is the key factor to improving the tensile strength of the alloy.