Understanding Evolution of Metal Microstructures during Dynamic Deformation at Atomic Scales and Mesoscales

The response of structural metallic materials under dynamic loading conditions is determined by the evolution of defects, their interaction with each other, and their evolution behavior that dictates the failure behavior. Understanding the different plasticity contributors in FCC, and BCC metals during various loading and unloading stages using experiments is a challenge due to the fast time scales of the processes at high strain rates. This talk will provide an overview of the current understanding of the shock response and identification of plasticity contributors that determine the dynamic (spall) strengths of FCC, BCC, and HCP microstructures as predicted using molecular dynamics (MD) simulations. The talk will highlight our new capabilities to characterize the deformation modes using virtual diffractograms and quantify the corresponding plasticity contributors using virtual texture analysis. Example simulations comprise shock loading and spall failure of FCC (Cu) and BCC (Ta, Fe) microstructures generated using MD simulations. The virtual characterization unravels the contributions of the deformation modes on the shifts, broadening, and splitting behavior of the various peaks/spots in the diffractograms for single crystal and polycrystalline Cu, Ta, and Fe, microstructures during shock loading and spall failure. This talk will also discusses combining a mesoscale modeling method “Quasi-coarse-grained dynamics” and virtual XRD to bridge the mesoscale gap in characterizing the plasticity contributions in FCC and BCC metals from slip, twinning, and phase transformation behavior.