An atomic view on the evolution of spall damage in solid-liquid mixed aluminum at high strain rates through stretching simulations

Using the classical molecular dynamic method, we investigated the evolution of spall damage through a series of stretching simulations for solid-liquid mixed aluminum at several initial temperatures. The results show that a turning point appears before void nucleation when the initial temperature is higher than 940 K in mixed Al at a strain rate of 3 × 108 s-1. The formation mechanism of the turning point is due to the local liquid phase nucleation. The growth of the local liquid phase gradually destroys the consecutive solid phases. The lower tensile strength of liquid Al than solid Al leads to the formation of the turning point. The voids tend to nucleate in the liquid phase in mixed Al at different initial temperatures except at 940 K. The time of void nucleation will be delayed due to the melting process before void nucleation in mixed Al. A nucleation and growth (NAG) model can describe the nucleation and growth of voids very well in mixed Al at 900, 920, 960, and 980 K. By adding the criterion of liquid phase proportion, the NAG model can also well describe the void volume fraction history of mixed Al at 940 K. We clarified the micro-mechanisms of spall damage evolution in mixed Al through tension simulation. The relevant results can provide a reference for future work on spall damage studies in solid-liquid mixed metals.