The role of grain boundary orientation on void nucleation in tantalum

Abstract

It is generally understood that microstructure plays a significant role in determining the deformation response of materials. During shock compression, grain boundaries serve as dislocation nucleation/pile-up/adsorption sites and grain size can alter the width of the shock front. During tensile release, grain boundaries are often “weak links” where spallation occurs. As such, a current deficit in predictive modeling capability is a quantitative description of these locations and their relative ability to serve as void nucleation sites - a challenging component of such a description is that spallation is inherently stochastic in nature. The inclination of the grain boundary plane with respect to the loading direction is thought to be a critical constituent in the resultant stress and failure at the boundary. Non-equilibrium molecular dynamics simulations are used to statistically quantify the influence of grain boundary inclination on the location of void nucleation and to highlight the emergence of stress hotspots at such boundaries. Boundaries oriented perpendicular to the loading direction are more likely to fail, but grain boundary inclination alone is not a complete predictor – i.e. not all perpendicular boundaries fail during spallation.