Crystal-melt coexistence in FCC and BCC metals: A molecular-dynamics study of crystal-melt interface free energies

Extensive molecular dynamics (MD) simulations are performed on six FCC and four BCC metals to calculate the crystal-melt interface free energies with the intention to compare systematically the structural influence. With a new method to stabilize the crystal-melt interface, the calculated interface free energies are in good agreement with the values from experiments, some existing simulations, and theoretical predictions. In particular, the anisotropies of the interface free energies are consistent with some experimental measurements and analytical models. In particular, the averaged interface free energy in FCC metals is found to be larger than that in BCC metals in general under the same conditions, which shows a strong dependence of the interface free energy on the crystal structures. Meanwhile, a trend towards a lower anisotropy in the interface free energy is found in BCC metals relative to that in FCC metals, which points to the importance of the influence of the interface free energy from the underlying crystalline structures. A Schematic illustration of the crystal-melt interfaces and their fluctuations in Cu for (100)[001] orientation. The atoms are colored based on order parameter Ψ, and the color of the atoms changes from red (melt) to blue (crystal) at the crystal-melt interface marked by dark lines and green atoms on the interfaces. (b) The interface profiles h(x) are extracted based on the positions of these “interface atoms”. [Display omitted]