Effect of grain boundary structure on plastic deformation during shock compression using molecular dynamics

Abstract

Grain boundaries (GBs) can play an important role in governing the mechanical behavior and damage evolution of a material during both quasistatic and dynamic loading. However, the general consensus of the shock physics community has been that minute details about the GB structure should not affect the response of a material to dynamic loading. In this paper, we present results of molecular-dynamics simulations investigating whether or not small changes in boundary structure are ‘recognized’ by the shock wave and can in turn affect the spall strength of a material. As a test case, we study a Σ11 asymmetric tilt GB in copper with an ordered and a disordered structure. The results are also compared with face-centered-cubic single crystals which correspond to the crystal orientations of the two grains in the bi-crystal. These results show that ordered and disordered boundaries undergo dissimilar amounts of plastic deformation during shock loading, which leads to spall strengths that vary by 12%, likely due to differences in the GB structures.