An ab initio molecular dynamics calculation of the density of the liquid metallic alloy Al–Si 12at% as a function of temperature

Abstract

The study of liquid metallic alloys using first principles Molecular Dynamic (MD) requires the knowledge of the liquid phase density that is not easy to obtain experimentally. In this work we calculate the densities for the liquid phase of eutectic Aluminium–Silicon alloy in the range of temperature from 856 K to 1270 K (The melting point for this alloy is 850 K). We build an atomic model in a periodic cubic cell with 125 atoms, 110 aluminium atoms and 15 silicon atoms. We then heat it from room temperature to the temperature of calculation T max, above the melting temperature, in 100 computational steps and we maintain the cell at this temperature ( plateau) during 100 computational steps. Finally we apply a volume optimization of the structure to find the desired density. This process is carried out several times until a minimum energy structure is reached. The results are compared with the experimental values.