Evading the low formability dilemma in Al-Zn-Mg-Cu alloys via heterogeneous structure

In order to evade the low formability dilemma in Al-Zn-Mg-Cu alloys, the formation mechanism of heterogeneous structure and its effect on the formability of Al-Zn-Mg-Cu alloys were systematically investigated. The results show that a heterogeneous structure with a co-existence of soft and hard microdomains can be formed by controlling and optimizing the thermomechanical processing. The formability of the alloys can be greatly enhanced, i.e., the average plastic strain ratio−r is increased from 0.6744 to 0.7502, which is mainly contributed to the coordinated deformation of soft and hard microdomains, and the weakened textures. In addition, both the formation mechanism of heterogeneous structure and high formability mechanism were put forward in this paper.