DETERMINATION OF BULK THERMODYNAMICS, TRANSPORT AND SURFACE PROPERTIES OF BINARY LIQUID Cd-Ga, Ag-Cu and Pb-Tl ALLOYS

Abstract

The mixing behaviour in binary liquid Ag-Cu, Cd-Ga and Pb-Tl alloys has been predicted through the study of various concentration dependent thermodynamic properties, surface and transport properties, as well as the microscopic functions in the frame of statistical mechanical theory in conjunction with self-association model (SAM). It was observed that at temperature T = 1423 K and 700 K for Ag-Cu and Cd-Ga liquid alloys, respectively, the computed 𝑠𝑐𝑐 (0)> 𝑆𝑐𝑐𝑖𝑑(0), which revealed a tendency for homo-coordination; hence both liquid Ag-Cu and Cd-Ga alloys are segregating systems. On the contrary, the calculated 𝑠𝑐𝑐 (0)< 𝑆𝑐𝑐𝑖𝑑(0) at 723 K for Pb-Tl alloy thus suggesting hetero-coordination of atoms in the alloy and compound formation is supported. The positive values of short range order parameter, 𝛼1 in the whole concentration range for binary liquid Ag-Cu and Cd-Ga alloys indicated presence of segregation while the negative values of 𝛼1 in Pb-Tl alloy suggested chemical ordering in the alloy. The surface properties examination via surface concentration and surface tension revealed that Ag atoms, Cd atoms and Pb atoms segregate respectively to the surface of Ag-Cu, Cd-Ga and Pb-Tl liquid alloys in the whole concentration. The surface tension isothermal plots of the three studied alloys show various degrees of segregation, both in the surface and in the bulk. Positive deviation in thermodynamic properties of Ag-Cu and Cd-Ga liquid alloys confirmed the two systems to be segregated liquid alloys while negative deviation in binary liquid Pb-Tl showed that it is an ordered alloy. Overall, the computed results compared quite reasonably well with the experimental data for each of the binary liquid alloys investigated.