Modification of the quasi-lattice theory for liquid alloys on the basis of varying the coordination number and its application to Al-Sn, Al-Zn and Sn-Zn

TL;DR

This paper enhances the quasi-lattice theory for liquid alloys by incorporating composition and temperature-dependent coordination numbers, improving predictions for properties of Al-Sn, Al-Zn, and Sn-Zn systems.

Contribution

It introduces a modified quasi-lattice theory that accounts for variable coordination numbers, providing more realistic modeling of liquid alloy properties.

Findings

Coordination number of 10 yields negligible approximation errors.

Modified QLT accurately predicts enthalpy and entropy of mixing.

Provides a foundation for applying QLT to ternary alloy systems.

Abstract

The existing quasi-lattice theory for liquid alloys (QLT), which has been extensively used by many researchers, has been modified by incorporating the knowledge of composition and temperature-dependent coordination numbers. The modified QLT was then used to compute the enthalpy of mixing, the entropy of mixing, concentration fluctuations, Warren-Cowley short range order parameter, surface concentrations and surface tensions of liquid Al-Sn, Al-Zn and Sn-Zn systems, which are the binary sub-systems for Al-Sn-Zn. The effect of the approximation of coordination number in the existing QLT was also investigated and was found to be insignificant when coordination number is 10. This work has provided a more physically realistic quasi-lattice theory, and has contributed to the knowledge on the binary subsystems of Al-Sn-Zn and has also set a foundation for the application of quasi-lattice theory on Al-Sn-Zn and other ternary systems.