Thermodynamic and transport properties of aluminium (Al)-based liquid binary alloys

Abstract

In this thesis, the thermodynamic and transport properties of Aluminum (Al) based liquid binary alloys (Al1xXx, here X=Zn, In, Sn, Bi, Cu, and Au) are systematically theoretically investigated. The thermodynamic properties of liquid binary alloys which are named as the free energy (A), the energy of mixing ( A), the enthalpy of mixing ( H) and the entropy of mixing ( S) have been studied. Atomic transport properties (ATP) such as the coe cients of shear viscosity ( ), the di usion coe cients (D), and the friction coe cients ( ) are theoretically calculated for Al-based liquid binary systems. On the other hand, for electron transport properties, I have also studied the electrical resistivity ( ) and conductivity theoretically. The general microscopic theory (GMT) is employed to describe the inter-ionic and electron-ion interactions of the above metals. The inter-ionic interaction and a reference liquid are the fundamental components of this theory. For understanding the inter-ionic interactions in the high temperature liquid state, the Bretonnet-Silbert (BS) model has been used and extended it for simple metals (Al, In, Sn, Bi). This model treats sp and d bands separately within the well established pseudopotential mechanism. A liquid of hard spheres (HS) of two di erent e ective diameters and charges is used to describe the reference system. The LWCA thermodynamic perturbative method is used to calculate the e ective hard sphere diameter and the partial structure factor, Sij (q). For studying ATP, the distribution function method has been used which was proposed by Rice-Allnatt (RA) and is very convenient for numerical calculations due to its simple form. More importantly, the physical signi cances of each term in the theory are very transparent for understanding various transport mechanisms involved. Besides, studying the ETP for di erent liquid binary alloys, extended form of Faber and Ziman (1965) formula has been employed to calculate the electrical resistivity. Ziman's theory is based on the Nearly Free Electron (NFE) model and predicting reasonable values for resistivity of liquid metals, and this theory has been extended here for liquid binary systems. In addition, I have also studied the thermodynamic and transport properties such as the excess entropy, the shear viscosity and the di usion coe cient using the Universal Scaling Laws (USL) proposed by Dzugutov for single system namely for Al. Excess entropy is the main ingredient in the USL. Results for both thermodynamic and transport properties of Aluminum (Al) based liquid binary systems agree well with the available experimental data.