Exploring high-pressure tantalum sound speeds and strength using multi-sample shock release experiments

Understanding the high-pressure strength and equation of state of materials is crucial for accurately modelling the dynamic deformation of materials. In this study, we used a two-stage gas gun to shock and release targets consisting of tantalum samples with a range of thicknesses. By monitoring the shock and release wave profile evolution at different thicknesses, we use an iterative characteristics analysis method to establish the sample sound speed – particle velocity (CL−up​) relations for shocked states between ~130 GPa and ~370 GPa. Continuous sound speed measurements are useful to constrain solid-liquid phase boundaries, material strength (if not melted), and release isentropes.

Our experimental approach provides high-quality velocity data and CL-up relations that reveal distinct features corresponding to solid, mixed-phase, and liquid tantalum. Our observations are consistent with previous experiments, but highlight that even when nearly melted, tantalum displays strength features – more than might be predicted by simple rate and temperature dependent strength models. This work enhances our understanding of tantalum's dynamic behavior under extreme conditions, contributing insights into the interplay of high-pressure phase boundaries and material strength.