Molecular dynamics modeling of the Hugoniot states of aluminum

In this study, molecular dynamics (MD) simulations coupled with multi-scale shock technique (MSST) are used to predict the Hugoniot curve PH, Gruneisen coefficient γ and melting temperature Tm of single crystal (SC) and nanocrystalline (NC) aluminum (Al) with grain sizes of 6 and 60 nm at dynamic high pressure. The linear relation between the shock wave velocity and particle velocity is reproduced, and the results indicate that there is nearly no difference for the Hugoniot of SC and NC Al, which could be explained by the fact that the grain size effect on PH can be negligible at high pressure. Some empirical models are used to predict γ and Tm, which exhibit an opposite behavior. In addition, it is found that the melting pressure and temperature are 107.5 GPa, 3063 K for SC Al, while they are 109.5 GPa, 3082 K for NC Al, which have a reasonable agreement with the published work.