Mechanical property and microstructure evolution of novel Al–Mg–Zn(–Cu) alloys under dynamic impact

Dynamic impact performance is one of the most important properties for lightweight aluminium armour vehicles. Here, we study the microstructure evolution of novel high-strength T-Mg32(AlZnCu)49 phase strengthened Al–Mg–Zn(–Cu) alloys during dynamic impact with strain rates from 2800 to 4800 s−1. Adiabatic shear bands appeared in both alloys after impact at 4800 s−1. Recrystallisation occurred inside ASB of the Cu-bearing alloy because of the higher temperature rise compared with Cu-free alloy. The negative change of flow stress is observed at 4800 s−1 for Cu-free alloy, but for Cu-bearing alloy that is positive at strain rates from 2800 to 4800 s−1, and the coarsening and decrease in the density of precipitates should be responsible for this rather than recrystallisation.