Structural and dynamical properties of liquid Al-Au alloys
HL Peng and T Voigtmann and G Kolland and H Kobatake and J Brillo, PHYSICAL REVIEW B, 92, 184201 (2015).
We investigate temperature-and composition-dependent structural and dynamical properties of Al-Au melts. Experiments are performed to obtain accurate density and viscosity data. The system shows a strong negative excess volume, similar to other Al-based binary alloys. We develop a molecular-dynamics (MD) model of the melt based on the embedded-atom method (EAM), gauged against the available experimental liquid-state data. A rescaling of previous EAM potentials for solid-state Au and Al improves the quantitative agreement with experimental data in the melt. In the MD simulation, the admixture of Au to Al can be interpreted as causing a local compression of the less dense Al system, driven by less soft Au-Au interactions. This local compression provides a microscopic mechanism explaining the strong negative excess volume of the melt. We further discuss the concentration dependence of self-and interdiffusion and viscosity in the MD model. Al atoms are more mobile than Au, and their increased mobility is linked to a lower viscosity of the melt.
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