Molecular dynamics calculation of solid liquid interfacial energy and anisotropy in U-Mo alloy system

Abstract

In this study, the solid-liquid interfacial energy and its anisotropy were quantitatively calculated in the U-Mo alloy system by using molecular dynamics simulations combined with the capillary wave method. After determining the equilibrium phase composition via Monte Carlo molecular dynamics, the interface location was identified using order parameters. The interfacial stiffness was extracted by fitting the relationship between the Fourier transform of the interface height and the wave number k, i.e., ${\left|A\left(k\right)\right|}^2\propto k^{-2}$. The results show that the average interfacial energy ${\gamma }_0$ increases with temperature (from 139.2 mJ/m² at 1450 K to 159.7 mJ/m² at 1600 K), and the ${\gamma }_0$ of the U-Mo alloy is higher than that of pure U (106.2 mJ/m²). The interfacial energy satisfies the anisotropy rule ${\gamma }_{110}\approx {\gamma }_{111}$ < ${\gamma }_{100}$. The anisotropy parameters ${\epsilon }_1$ (0.0066–0.0085) and ${\epsilon }_2$ (0.0012–0.0019) reveal the crystal orientation sensitivity of the interfacial stiffness and the anisotropy of different crystal planes, which can provide key parameters for phase-field simulations.