Thermodynamic and surface properties of Al–Li–Mg liquid alloy

The theoretical calculation was carried out for thermo-physical functions, such as excess Gibbs free energy of mixing, activity, enthalpy of mixing, and surface tension, for liquid Al–Li-Mg ternary alloy at temperatures 1000 K, 1073 K, 1150 K, and 1250 K for the production of a thermodynamic database. For this purpose, the T-dependent interaction parameters of Redlich-Kister (R–K) polynomials for binary sub-systems were optimized, which were used to compute the excess Gibbs free energy of mixing for liquid Al–Li–Mg ternary alloy based on GSM, Toop, and Kohler models. The computed partial excess Gibbs free energy of mixing were used to determine the activities of the monomers of the binary sub-systems and ternary Al–Li–Mg system. The exponential T- dependent parameters have been optimized and used to calculate the enthalpy of mixing for the ternary system. Using the theoretically determined partial excess Gibbs free energy of constituent elements of the alloy, the surface tensions of binary sub-systems were calculated employing Butler’s equations. Further, the coefficients of T- dependent R–K polynomials have been optimized for excess surface tensions of binary subsystems, which were used to compute the surface tension of the ternary system using the models mentioned above.