Sub-grain formation in Al-Li-Mg-Zn-Cu lightweight entropic alloy by ultrasonic hammering

In this paper, the ultrasonic hammering treatment is applied to the lightweight entropic alloy Al80Li5Mg5Zn5Cu5, contributing to the modification of coarse microstructures and the improvement of mechanical properties. The effects of ultrasonic hammering on the microstructures and mechanical properties of Al80Li5Mg5Zn5Cu5 are elaborately studied, and the formation of sub-grains is thoroughly analyzed. Results show that the coarse dendrite structure is crushed into diffusely distributed micron-sized particles, and the grain size is refined significantly from larger than 200 mu m to about 5 mu m, along with the formation of sub-grains during instant dynamic recovery. Microhardness and modulus of the grain-refined alloy increase by 50% and 22%, respectively, compared to the coarse-grained counterpart without ultrasonic hammering.