The Anisotropic Free Energy of the Solid-Liquid Phase Boundary in Al

Abstract

We have performed large-scale molecular dynamics simulations of solid-liquid interfaces in aluminum, in order to calculate their interfacial stiffness and free energy. The anisotropy of these properties, though small, is key for determining the steady-state solutions for solidification in three dimensions. We find that the interfacial free energy, γ(θ), can be well represented by the form γ(θ) = γ0(1 + e cos 4θ, where θ measures the angle relative to the [100] interface, rotating about a [001] direction. We find values of γ0 = 120 ± 6 mJ/m2 and e = 1.3 ± 0.4%, in agreement with previous estimates and current experimental results.