Temperature dependence of the bulk and surface properties of liquid Zn–Cd alloys

Abstract

The effects of temperature on the bulk and surface properties of liquid Zn-Cd alloys have been theoretically investigated, using a combination of self association model, Darken's thermodynamic equation for diffusion, empirical model for viscosity and a statistical mechanics model. The results from this study show that change in temperature resulted in cross-over effects in bulk and surface properties. We also found that with an increase in temperature, a pronounced asymmetry of viscosity isotherm is significantly reduced, and viscosity isotherm exhibited anomalous behaviour. Our results reveal that the homocoordination tendency in Zn-Cd liquid alloys is not strong and reduces with increasing temperature. The study further suggests a pronounced segregation of Cd-atoms at the surface of Zn-Cd liquid alloys and the extent of segregation reduces with temperature. We as well found that, in addition to the reported understanding that size-factor determines the compositional location of asymmetry of the viscosity isotherm, temperature is an operating parameter that has effect, not only on the composition of asymmetry, but also on the magnitude of asymmetry. In all the properties investigated, the most pronounced effect of temperature (52.9%) is on the viscosity while the least effect (7.1%) is on the surface tension.

Application of the molecular interaction volume model to the assessment of thermodynamic properties of liquid Zn-Bi alloys

“…3 shows the demixing tendencies in Zn-Bi liquid alloy at all the temperatures albeit at varying degrees. This is an indication that Zn-Bi liquid alloys are homocoordinated and that the homocoordination which is strong is indicated by the relatively high peak at various temperatures when compared with weakly homocoordinated alloys like Zn*Cd liquid alloys [24]. It should be noticed that there is a relatively large reduction in the peak value of S xx (0) as the temperature increased from 923 to 1023 K. This trend in the reduction of the peak value of S xx (0) suggests some form of the reduction in the demixing tendencies of this alloy with an increase in temperature.…”

“…It has been reported that transport properties such as diffusivities of metals in the liquid state are needed for many metallurgical processes [24]. Also, from the practical point of view, the viscosity is reported to be one of the key parameters for the design and optimization of metallurgical processes [25].…”

Theoretical Analysis of the Thermodynamic, Structural, Surface and Transport Properties of PbSn Liquid Alloys at 1050 K

“…0.2484 at 𝐶𝐶𝑃𝑃𝑃𝑃= 0.8 and then increases. This indicates that the possibility of phase separation is maximum around 𝐶𝐶𝑃𝑃𝑃𝑃= 0.8 [16]. It should be pointed out that no experimental data for of PbSn system at 1050 K have been introduced in Fig.…”

“…In self association model, the constituent atoms are supposed to be comparable in size (or volume) which may be applicable for Pb and Sn atoms. For four decades, self association model [13] has been adequately applied [14][15][16][17] to explain the bulk and surface properties of binary liquid alloys such as CdGa, AlSn, SnTl, CdZn, BiSn etc. Section-2 deals with the analytical equations for the thermodynamic, structural, surface and transport functions of a binary system in molten state in the framework of self association model.…”