Characterizing Pressure-Temperature States during Shock Compression and Shock Release in Metals using Molecular Dynamics Simulations

Shock experiments are typically used to understand microstructural evolution at extreme pressures and temperatures and map phase boundaries to develop the equation of state (EOS). While rear surface velocity profiles enable the characterization of the shock Hugoniot in experiments, the understanding of microstructure evolution at these states is limited to in-situ x-ray diffraction (XRD). The ability to interpret the local pressure and temperature states generated during shock-induced melting and phase transformations, as well as phase fractions remains a challenge. This talk presents the applicability of molecular dynamics (MD) simulations to predict these extreme states and complement the interpretation of experimental diffraction patterns using model FCC (Cu) and BCC (Fe) systems. MD simulations are carried out to characterize the EOS and identify thresholds of melting in Cu and BCC-HCP transformation in Fe under shock loading conditions. Deformed microstructures are characterized using virtual XRD to unravel the interplay between pressure, temperature, and phase in order to inform states obtained experimentally. This talk will discuss our approach to develop a framework to couple MD simulations with experimental techniques to characterize the pressure-temperature states.