Shear Viscosity of Liquid Gold, Copper, and Gold-Copper Alloy

Y. Qi, T. Cagin, K. A. Mansour, Y. Kimura, W. A. Goddard

Abstract

Using NEMD method we have calculated the shear viscosities of Au, Cu and Au-Cu alloys at elevated temperatures. The interactions for Cu, Au and Au-Cu alloy are represented by a many-body potential form due to Sutton and Chen, but the parameters for the potentials are modified to accurately represent phonon spectra and vacancy and surface formation energies [Kimura, Cagin and Goddard]. Using 500 atom model systems and the experimental density at each temperature we calculated the viscosity at a number of shear rates for the model systems at temperatures up to 2000K. The predicted viscosity are in good agreement with experiment. Copper-Gold alloy simulations are carried out at three different concentrations , 25%, 50% and 75%. The dependences of shear viscosity on shear rate, concentration, temperature and desity are investigated.