Study of excess free energy of mixing and heat of mixing of liquid ternary Al–Li–Zn alloy by assessing the thermodynamic properties of sub-binary alloys

Abstract

The exponential temperature-dependent interaction parameters of the Redlich-Kister (R–K) polynomial for the binary sub-systems of the liquid Al–Li–Zn ternary alloy were optimized using available literature data. The ternary interaction terms of the Redlich-Kister-Maggianu (R–K–M) polynomial were then optimized in order to determine the excess Gibbs free energy of mixing (GMxs) and the enthalpy of mixing (HM) of the system. These functions for the liquid ternary alloys were also computed at temperatures of 973 K, 1273 K and 1573 K. The calculated inverted miscibility gap that appeared in GMxs while using the linear temperature-dependent interaction parameters was suppressed in this work by the assumption of the interaction parameters to be exponential temperature dependent. The enthalpy of mixing of the alloy so calculated was found to be in good agreement with the available experimental data.