Atomistic modeling of plane shock loading in high strength ceramics
Paulo BRANICIO (IHPC)
Materials for Extreme Environments: Multiscale Experiments and Simulations
Mon 4:20 - 5:40
Salomon 203
Molecular-dynamics simulations of plane shock loading are performed to reveal the generation and interplay of shock-induced compaction, structural phase transformation and plastic deformation in SiC and AlN ceramics. The induced shock profile is calculated for a wide range of particle velocity from 0.1 km/s to 6 km/s, to fully characterize the shock Hugoniot, and along different crystallographic directions, to investigate load path dependencies. The calculated Hugoniot curves agree well with that from experiments. The observed nanoscale structure of the shock waves is composed of an elastic precursor, structural transformation wave, and overdriven wave for increasing shock intensity. For both SiC and AlN the structural phase transformation drives the system to the compact rock salt phase, from the zinc blend phase at 90 GPa, for SiC, and from the wurtzite phase at 20 GPa, for AlN, respectively. While twinning is present for the cubic structure (zinc-blend) of SiC is is completely absent from the hexagonal structure (wurtzite) of AlN. For SiC a well defined twinning based plastic wave is generated ahead of the transformation wave for shocks on the [001] and [111] directions. These simulation results provide an atomistic view of the dynamic effects of shock impact on single crystal high-strength ceramics.