Effect of Zn/Mg Ratio on Microstructure and Properties of Cold Extruded Al- x Zn-2.4Mg-0.84Cu-0.2Zr-0.25Ti Aluminum Alloy

The effect of various Zn/Mg ratios on the microstructure and properties of cold extruded Al-xZn-2.4Mg-0.84Cu-0.2Zr-0.25Ti aluminum alloys was investigated. The microstructure analyses showed that as the Zn/Mg ratio increased from 3.46 to 3.84 and to 4.04, the recrystallization degree and the undissolved phase gradually increased. Moreover, with the increasing Zn/Mg ratio, the grain size of the alloy was refined, and the dislocation strengthening effect firstly increased and then decreased. The mechanical test results showed that as the Zn/Mg ratio increased from 3.46 to 3.84 and to 4.04, the tensile strength and hardness of the cold extruded Al-xZn-2.4Mg-0.84Cu-0.2Zr-0.25Ti alloy firstly increased and then decreased. The alloy with lower Zn/Mg ratio exhibited better capacitor characteristics, surface protection and corrosion resistance.