Microscopic Mechanism Of Void Evolution In Copper Under Shock Loading Along 〈111〉 Direction

Dynamic fracture of materials is a multi-scale phenomenon. Deep understanding of dynamic fracture necessitates the studies at different time and spatial scales. There have been many researches based on traditional macroscopic experimental methods and continuum theories, and through these methods a lot of achievements were obtained. As we know more about dynamic fracture, the importance of the atomistic information becomes much clear for fully understanding of dynamic fracture. However, due to the limitation of spatial and time scale, it is not able to directly observe the atomistic pictures of dynamic process in near future. Furthermore, because materials have discrete nature, continuum treatments are difficult to be applied to atomistic scale.Spallation is a fracture phenomenon under dynamic tension. Previous research results about ductile metals have shown spallation consists of three stages:void nucleation,growth,and coalescence. However, it is still not enough to understand microscopic mechanism about them due to limitation of experiment conditions and the theory. In this work, evolution of nano-void in single crystal copper under shock loading is investigated by means of MD. The microscopic mechanism and quantitative law of void growth are obtained under <111> shock loading. In addition, the microscopic process of plasticity deformation around the void is also observed and analyzed with elastic theory of dislocation.