Shocked ceramics melt: An atomistic analysis of thermodynamic behavior of boron carbide
Matthew DeVries, Ghatu Subhash, Amnaya P. Awasthi
Abstract
Macroscale experiments for structural response of materials often do not capture deformation features at the atomistic scale. This limitation becomes more pronounced in materials subjected to shock loading, especially in covalently bonded ceramics such as boron carbide, which exhibit a deleterious mechanism called pressure-induced amorphization. Perhaps because ceramics have high thermal resistance, temperature was never considered a prime factor influencing deformation mechanisms, leaving such phenomena unexplained for more than two decades. In this article, we probe fundamental material behavior using molecular dynamics (MD) to link nanoscale thermodynamics to amorphization during shock loading. We have generated Rayleigh lines via MD shock simulations, subsequently constructing the shock Hugoniot, which aligns well with experimental data. We estimate shock-induced temperature in ceramics to be well above their melting point, resolving a plethora of interconnected scientific issues pertaining to anomalous behavior of boron carbide.