A Molecular Dynamics Study of Partitionless Solidification and Melting of Al-Cu Alloys

The partitionless solidification and melting in Al-Cu alloy system are investigated by means of molecular dynamics simulations with an embedded atom method (EAM) potential. The solid-liquid interfacial velocity for solid-liquid biphasic systems of Al-rich alloys is examined with respect to temperature and Cu composition. The kinetic coefficient is then derived from the slope of the interfacial velocity with respect to temperature. Our results show that the kinetic coefficient is largely dependent on the Cu composition. It sharply decreases with addition of small amount of Cu. There is almost no partition at the solid-liquid interface within the time scale of the simulation since the solid-liquid interfacial velocity is very fast at temperatures away from the equilibrium temperature. Since it is not straightforward to measure the kinetic coefficient directly from experiments, it is significant in this study to derive the composition dependence of the kinetic coefficient for binary alloys directly from the MD simulation without any phenomenological parameters.