Structure and properties of liquid Al-Cu alloys: Empirical potentials compared

We report on the structure and mass transport properties of liquid Al-Cu alloys predicted by two recently-developed empirical many-body potentials: MEAM (Jelinek et al., 2012) and EAM-ADP (Apostol and Mishin, 2011), and by the well-known Gupta potential. Total and partial pair correlation functions, angular distribution functions, densities, coordination numbers and self-diffusion coefficients are compared with published experimental and ab initio results for a number of temperatures above the liquidus. Prevalent local orderings are characterized by means of Voronoi analysis. Densities and the temperature coefficient of density are compared with experiment for different compositions of the alloy. All three studied potentials, and EAM-ADP and MEAM in particular, display marked difficulty in describing mixed (Al-Cu) interactions. EAM-ADP mispredicts Cu-rich alloys to re-solidify at all temperatures studied, while MEAM's predictions for the density and its temperature dependence are poor for Al-rich compositions. Overall, the best description of liquid Al-Cu is offered by the Gupta potential, which is found to give a reasonable picture of short-range order and predicts mass transport coefficients and densities in moderately good agreement with experiment. (C) 2015 Elsevier B.V. All rights reserved.