Densities of Au-X (X = Cu, Ni and Pd) binary melts and thermodynamic correlations.

• The thermophysical properties of Au-X (X = Cu, Pd and Ni) melts were assessed. • Measurements were performed using a levitation method with a static magnetic field. • Binary systems having an order–disorder transition had positive V E and negative G E. • Binary melts were sorted into four groups using the correlations between V E and G E. Our group has previously investigated the correlations between the excess volumes, thermodynamic functions and phase diagrams of binary alloy melts, and the present study focused on binary Au-X (X = Cu, Pd and Ni) alloy melts. The Au-Cu and Au-Pd systems have intermetallic compounds with order–disorder transitions. The densities of these alloy melts were determined with small uncertainties using a combination of an electromagnetic levitation technique and a static magnetic field. The densities of these melts varied linearly with temperature, including those temperatures within the supercooled range. These results are discussed herein within a thermodynamic framework based on the correlation between excess volume (V E) and excess Gibbs energy (G E). The data obtained in this work confirmed that binary alloy systems having an order–disorder transition, such as the Au-Cu and Au-Pd systems, belonged to the group defined by V E ≥ 0 and G E < 0. The effect of composition on V E was examined with regard to cluster formation in the liquids. The Au-Ni system was shown to possess a miscibility gap in the solid solution and the corresponding melts had positive V E and positive G E values. [ABSTRACT FROM AUTHOR]