Structure and dynamics of liquid Al1−xSix alloys by ab initio molecular dynamics simulations

First-principles molecular dynamics (MD) simulations are performed to study the structure and dynamics of liquid Al1−xSix (x = 0.0, 0.12, 0.2, 0.4, 0.6, 0.8) at the temperature of 1573 K. The composition dependence of static structure factors, pair correlation functions, and diffusion constants are investigated. We found that the structure of the liquid Al1−xSix alloys is strongly dependent on the composition. From our simulation and analysis, we can see that although liquid Al1−xSix is metallic, there are some degrees of covalent tetrahedral short-range order in the liquid. The degree of tetrahedral short-range order increases linearly as the Si concentration in the liquid increased. The diffusion coefficients of both Al and Si atoms in liquid Al1−xSix alloys at 1573 K are not very sensitive to the composition.