O.E. Awe

Thermodynamic properties of liquid Te-Ga and Te-Tl alloys

Abstract We have used a statistical mechanics model based on the assumption of compound formation in binary alloys to study the bulk and surface properties of Te–Ga and Te–Tl liquid alloys. The assumption of appropriate complexes, specifically, equiatomic TeGa for Te–Ga alloys and Tl 4 Te for Te–Tl in conjunction with the model enables us to gain a better insight into the nature of order in the two liquid alloys. Using the basic interaction parameters that characterize the model, we have been able to compute the bulk thermodynamic properties of the alloys. Essentially, from our calculations, we are able to show that the Te–Ga liquid alloy is one that undergoes an order–disorder transformation depending on the proportion of Te in the alloy. The Te–Tl system on the other hand exhibits compound formation over the whole composition range. With regards to surface properties, at lower concentration Te segregates more to the surface in Te–Ga alloys than in Te–Tl, however, at higher concentrations the two alloys exhibit quantitatively similar features in the composition dependence of surface concentration.

Thermodynamics of liquid Al - In, Ag - In and In - Sb alloys from a four-atom cluster model

Abstract A model based on a cluster of four atoms has been used to obtain higher-order conditional probabilities that describe the atomic correlations in Al–In, Ag–In and In–Sb liquid alloys. Using the value of the ordering energy obtained from the model, some thermodynamic quantities such as Gibbs energy of mixing and concentration-concentration fluctuations in the long wavelength limit were calculated for these alloys. Our study of the energetics of these liquid alloys reveals that while In– Sb and Ag–In are both chemically ordered or heterocoordinated systems, Al–In is a segregating system. Furthermore, the degree of order in liquid In–Sb alloys is higher than that in liquid Ag–In alloys.

Thermodynamic investigations of Bi - Cd, In - Pb, and Ni - Pd liquid alloys

Abstract A model based on the existence of self-associates has been used to compute bulk thermodynamic properties of Bi–Cd, In–Pb, and Ni–Pd binary liquid alloys. Also, a statistical mechanics model has been employed to calculate the surface properties of these three alloys. Our study reveals that the degree of phase separation increases in the order Bi–Cd, In–Pb and Ni–Pd. Essentially, we find that Bi–Cd, like Au–Bi and Bi–Sb alloys, does not belong exclusively to the class of either segregating systems or to the short-range ordered alloys. Furthermore, we were able to predict the temperature dependence of the surface properties for our binary liquid alloys based on the knowlege of the results at their melting points.

A QUASI-LATTICE THEORY FOR COMPOUND FORMING TERNARY LIQUID ALLOYS

A Quasi-lattice model of liquid binary mixtures has been used to establish a model for calculating some thermodynamic properties of compound forming ternary liquid alloys. The effect of varying Z on the concentration fluctuations was also investigated. Results obtained for limiting case of the model are presented and compared with that obtained by Bhatia and Singh for binary liquid alloys. A framework for calculating the Warren Cowley short range order for ternary liquid alloys as a function of Z is also formulated.