Molecular-dynamics study of melting on the shock Hugoniot of Al

Abstract

We investigate the Hugoniot melting point of Al using a molecular-dynamics approach based on an embedded-atom method. We calculate the Gibbs free energies of the crystalline and liquid phases as a function of pressure and temperature using the coupling-constant integration method and obtain the melting curve up to 1.6 Mbar, in good agreement with experiments. We also examine the melting properties near zero pressure. The Hugoniot equation of states (EOS) up to 1.8 Mbar is obtained from the Rankine-Hugoniot relation and the isotherms determined for different temperatures. Comparing the melting curve with the Hugoniot EOS's for the solid and liquid phases, the Hugoniot melting is found to begin at 1.2 Mbar and to end at 1.4 Mbar, consistent with shock-wave data. [S0163-1829(99)02301-2].