3D characterization of shock-induced damage in wrought Ta

Predicting the failure of crystalline materials requires knowledge of the underlying failure mechanisms and their dependence on microstructure. When undergoing high strain rate deformation, ductile metals generally follow a pathway of nucleation, growth, and coalescence of voids followed by failure. In order to adequately model and predict deformation in these circumstances, a fundamental understanding of these complex, three-dimensional processes is required. While analysis of 2D sections can provide some insight into these mechanisms, the ability to quantify the impact of key microstructural features such as triple junctions and quadruple points is severely limited. In this study, a 3D-EBSD characterization experiment is performed on high-purity tantalum prior to and after partial spallation by plate impact, which allows for the statistical assessment of the microstructural neighborhoods surrounding incipient voids. In analyzing the resulting dataset containing 5884 grains and 467 voids, it is observed that the voids were roughly spherical and consistent in size throughout the spalled material. The voids are most likely to reside at quadruple points, at triple junctions, at grain boundaries, and within grains, in decreasing order of prevalence. Moreover, voids tend to form at grain boundaries with high degrees of plastic incompatibility, growing into the plastically soft grain but orienting primarily with or perpendicular to the loading direction.