Predicting failure stress for grain boundaries using average and local properties

Abstract

Several factors can affect the failure stress of a grain boundary, such as grain boundary structure, energy and excess volume, in addition to its interactions with dislocations. In this paper, we focus on the influence of grain boundary energy, excess volume and plasticity at the boundary on the failure stress of a grain boundary, in copper from molecular-dynamics simulations. Flyer plate simulations were carried out for four boundary types with different energies and excess volumes. These boundaries were chosen as model systems to represent various boundaries observed in "real" materials. Simulations indicate that there is no direct correlation between the void nucleation stress of a boundary and either its energy and excess volume. This result suggests that average properties of grain boundaries alone are not sufficient indicators of the failure strength of a boundary. However, local boundary properties related to the ability of a grain boundary to undergo plastic deformation are better markers of its strength. © Published under licence by IOP Publishing Ltd.