Synergistic improvement of strength and ductility of an ultra-high strength Al-Zn-Mg-Cu alloy through a new aging strategy

In this paper, a high-alloyed Al-Zn-Mg-Cu alloy with excellent combination of strength and ductility using a new aging strategy was studied. The results show that high density and fine age hardening precipitates, overlap precipitates and uniformly distributed dislocation structure were formed after new aging strategy. The ultimate tensile strength value of 813 +/- 2 MPa and elongation of 6.0 +/- 0.2 % of the studied alloy can be achieved, which show substantial advantages compared to other Al-Zn-Mg-Cu alloys reported before. The outstanding mechanical properties owe to the pre-precipitated GP zones and uniformly distributed dislocations introduced by the combinatorial pre-treatment including natural aging, pre-stretching and a short-term low-temperature aging.