Hardness, quench sensitivity, and electrical conductivity of 7xxx Al alloys with high Zn concentrations

In this study, 7xxx (Al-Zn-Mg-Cu) alloys with high Zn concentrations were fabricated by increasing the Zn contents of 7085 Al alloys. The hardness, quench sensitivity, and electrical conductivity of the alloys and a 7085 Al alloy under peak-aged state were studied. The high Zn concentration alloys had higher η′ phase densities and lower quantities of Mg solid atoms than the 7085 Al alloy and thus exhibited higher hardness and electrical conductivity. The high Zn concentration alloys also exhibited slightly higher quench sensitivity than 7085 Al alloy, and the depth of the quenching layer of the alloy with 11.27 wt% Zn content reached 100 mm. This work confirmed that the novel 7xxx alloy with high Zn concentration showed balanced performance, exhibiting enhanced hardness and conductivity and reasonable quench sensitivity compared with the 7085 commercial Al alloy.