Computing the solid-liquid interfacial free energy and anisotropy of the Al-Mg system using a MEAM potential with atomistic simulations

The solid-liquid interfacial free energy, gamma, and its associated anisotropy were computed for the Al-Mg binary alloy system using Molecular Dynamics (MD) simulations in conjunction with the capillary fluctuation method (CFM). Interactions between atoms were modeled based on a second nearest neighbor modified embedded atom method (MEAM) potential, a successor to the established embedded atom method (EAM) potential. The MEAM potential predicts a melting temperature of 938 K +/- 17 K for pure Al and the solid-liquid phase equilibria as a function of temperature and composition was found using Monte Carlo technique implemented in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The average interfacial free energy, gamma 0, for pure Al was found to be 135.94 +/- 3.62 mJ/m2 which agrees well with experimental values and an interfacial free energy relationship of gamma 100 > gamma 110 > gamma 111 was found across the majority of the temperatures which is consistent with FCC metals. The anisotropy values were found to fall within the 100 growth direction along the orientation selection map suggesting the addition of Mg stabilizes this growth direction. The results from the MEAM potential compares qualitatively well with other EAM potentials, however, experiences larger errors at lower temperatures.

Automated summary

The solid-liquid interfacial free energy and anisotropy of the Al-Mg binary alloy system were studied using MD simulations and CFM. The MEAM potential predicted the melting temperature and phase equilibria of the system. The interfacial free energy was found to agree with experimental values, and anisotropy was observed in the growth direction.