Wave speeds in single-crystal and polycrystalline copper

Abstract

There is a need in the scientific community to improve predictive hydrodynamic codes. Empirical data are necessary to improve and constrain these models. This work considers the potential differences between the shock Hugoniots of single-crystal and polycrystalline copper. Polycrystalline materials are composed of grains of randomly oriented single crystals, so knowledge of these is necessary to build mesoscale representations of bulk materials. In this work, we measure the shock speeds of three different orientations of single-crystal copper, [100], [110], and [111], as well as polycrystalline copper. Symmetric planar impacts with a “top hat” target design provide timing information for the elastic and plastic waves. We use a comparison of ultrasonically measured ambient longitudinal sound speeds with the elastic wave speeds at pressure to constrain error bars for our analysis. Our results show that differences between the various orientations of single-crystal copper and polycrystalline copper are within the error of the experiment.