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The thermodynamic properties of liquid In-Sn alloys indicate a weak interactions between unlike atoms. The new In, Sn and In-Sn surface tension experimental data set obtained by the large-drop method over the temperature range 523-923 K together with the literature data on different thermophysical properties substantiate a nearly ideal mixing behaviour of these alloys. A low interaction energies do not effect the composition dependence of thermophysical properties, in particular the surface tension and the surface segregation. In order to estimate the effects of the short-range order phenomenon on the surface properties of In-Sn liquids, the QCA (quasi chemical approximation) for the regular solution model and the CFM (compound formation model) have been applied. In the same framework the transport properties and the structural characteristics of liquid In-Sn alloys have also been analysed.

The applicability of quasi-lattice theory (QLT) to describe surface and transport properties of Ag-Cu liquid alloys is substantiated by surface tension experimental data. The surface tension of molten Ag, Cu and Ag-Cu alloys has been measured by the pinned-sessile drop method over a temperature range. The results obtained are in good agreement with other reported measurements on pure elements and their alloys as well as with calculated surface tension values. The phase diagram of Ag-Cu system shows the existence of a simple eutectic indicating a tendency towards phase separation. The mixing behaviour of Ag-Cu regular alloys has been analysed through the study of surface properties (surface tension and surface composition), dynamic properties (chemical diffusion and viscosity) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the frame of quasi-lattice theory combined with a statistical mechanical theory.

The present work is an experimentally based investigation of the applicability of the complex formation model (CFM) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory (QLT) to describe the surface and transport properties of Au–Sn liquid alloys. Depending on melting temperatures, the surface tension of molten Au and Au–Sn alloys has been measured by the pinned-large drop method in the temperature range of T = 1275–1493 K. The calculations have been done with various objectives in view, i.e., to analyse existing thermodynamic data related to the peculiarities of the Au–Sn phase diagram, to use these data as the input for the interaction parameter calculations, to calculate the surface properties (surface tension and surface composition) and to compare the computed data with a new set of the surface tension experimental data as well as to predict the values of dynamic properties (chemical diffusion and viscosity). Some information on the structure of Au–Sn liquid alloys are given in terms of the microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter).