Temperature dependence of the thermodynamic functions of strongly interacting liquid alloys

A model is proposed to obtain expressions for thermodynamic functions like the heat of mixing (H_M), excess specific heat ( Delta C_P), volume of mixing (V_M) and isothermal compressibility ( chi _T) of liquid binary alloys with a strong compound-forming tendency in order to cover a large range of temperature. This has been used to analyse the temperature dependence of the free energy of mixing (G_M), H _M and Delta C_P for liquid Li-Sn alloys. The specific heat of the liquid Li₇Sn₂ alloy has been determined experimentally by drop calorimetric heat content measurements and is found to support the theoretical value, which is based on EMF analysis. The results indicate self-coordination towards the Sn-rich end and strong hetero-coordination in the region 0.33<or=c_Li<or=1.0, being maximum around Li₃Sn. The influence of the chemical short-range order (CSRO) on the concentration fluctuations, S_cc(0), chemical diffusion, D, and order parameter, alpha ₁, has been considered. S_cc(0) registers a dominant temperature effect in the self-coordinated region, whereas the effect of temperature on the diffusion coefficient is most visible in the hetero-coordinated region.