Thermodynamic and structural behaviour of Tl-Na liquid alloy

Abstract

In this work we intend to study the thermodynamic and microscopic structural properties of Tl-Na liquid alloy at 673 K on the basis of regular associated solution model. We have estimated the mole fractions of the complex and the free monomers assuming the complex TlNα as energetically favoured in the initial melt. In thermodynamic properties, we have computed free energy of mixing (G_M), enthalpy of mixing (G_M), entropy of mixing (S_M) and activities of the monomers (α_Tl and α_Nα). The compositional contributions of the heat of mixing and the heat of formation of the complex to the net enthalpy change have also been studied. The microscopic structural properties of the alloy have been studied by computing concentration fluctuation in the long wavelength limit (S_CC(O)), chemical short range order parameter (α₁) and the ratio of mutual to intrinsic diffusion coefficients (D_M/D_id). Both the theoretical and the experimental values of S_CC(O) are found to be less than the ideal values at all compositions which indicates the ordering nature of Tl-Na liquid alloy at 673 K. All the interaction energy parameters are found to be negative and temperature dependent. The liquid system is found to be moderately interacting.

DOI: http://dx.doi.org/10.3126/bibechana.v12i0.11784

BIBECHANA 12 (2015) 20-29