Thermophysical properties of undercooled liquid Au–Cu alloys from molecular dynamics simulations

The density and the specific heat of liquid Au–Cu alloy above and below the melting temperature are investigated in a wide composition range via constant temperature and constant pressure molecular dynamics simulations. The atomic interaction of the alloy is described with the embedded-atom method (EAM). The equilibrium melting temperature is evaluated from the change in the growth direction of a crystal–liquid sandwich structure under annealing. The simulated density of the Au–Cu alloy increases linearly with decrease of the temperature, whereas the specific heat remains constant over the entire temperature range of 900–1900 K. The excess volume is calculated according to the predicted density of Au–Cu alloy. The negative value of the excess volume and the exponential concentration dependence of the specific heat indicate that the Neumann–Kopp rule does not apply to the Au–Cu binary alloy system.