Investigating effect of disorder degree on thermodynamic properties in Cu3Au alloy from pseudo-atomic potentials

While the Cu3Au alloy, as an archetype, is often used to investigate the transformation from fully ordered to fully disordered phases, very limited studies focused on the difference of the thermal performance between the Cu3Au alloys with different disorder degrees. In this work, we propose the pseudo-atomic potential (PAP) and use the elegant Chen-Möbius inversion method to extract the PAP for Cu3Au from the available experiments. The validity of PAPs is evaluated by the consistence of our calculated equilibrium bulk properties, vibrational entropy difference between the ordered and disordered alloys with the available results and the simulation of molecular dynamics on the thermal expansion coefficient of Cu3Au. Based on the PAP, we study the thermodynamic properties and the order-disordered transformation temperature for the Cu3Au alloy with different disorder degrees. We predict the positive specific heat capacity difference between the disordered and ordered alloys.