Super-high formability of Al-5.0Zn-1.5Mg-1.5Cu (wt.%) alloy via gradient heterogeneous structure

A novel idea of precisely constructing gradient heterogeneous microstructure was proposed to greatly improve the formability of Al-Zn-Mg-Cu alloy by coupling multi-process firstly. After coupling control of the heterogeneous distribution of precipitates, strain energy storage and dislocation number density, a gradient distribution of coarse/fine grains can be constructed in the pre-aged alloy, resulting in a greatly enhanced average plastic strain ratio of 0.716. This work opens up a new frontier for achieving super-high room temperature formability without sacrificing the high strengths for Al-Zn-Mg-Cu alloys.