Research On Comparison Of Wilson,T-K-Wilson And NRTL Equations In The Calculation Of The Thermodynamic Properties Of Liquid Alloys

In this paper, thermodynamic properties of 89 binary liquid alloys have been investigated by local composition models including Wilson equation, T-K-Wilson equation, and NRTL equation. The result shows that local composition models are particularly well- suited for moderate deviation systems; and for strong positive deviation systems, NRTL equation fit gives little more acceptable results than T-K-Wilson equation one, however, Wilson equation is inadequate; for strong negative deviation systems and reciprocal deviation ones, local composition models fail. Then, on the basis of above achieved constituent binary results, thermodynamic properties of 10 ternary liquid alioys (Cd-Bi-Pb, Cd-Pb-Sb, Cd-Pb-Sn, Mg-In-Cd, Zn-In- Cd, Cd-Bi-Sn, In-Bi-Pb, Sn-AgPb,Zn-In.Pb, Al-Cu-Zn), 3 quaternary ones (Cd-Bi-Pb-Sn, Zn-Sn-Cd-Bi, Zn-Sn-Cd-Pb) and 1 quinary. one (Zn-Sn-Pb-Cd-Bi) are predicted. For most of investigated multicomponent systems, the calculated activities are in good with the experimental ones, and in particular for multicompoment immiscible ones, the predicted results are satisfactory and exciting. At the same time, the comparison result between the three equations shows that Wilson equation and T-K-Wilson one are more stable than NRTL one, that maybe is because NRTL equation contains a third parameter, and so ,to some degree, Wilson model and T-K-Wilson model are superior to NRTL model. And also the comparison between local composition models and other models such as Pelton- Flengas?method, Krupkowski formalism, mass action concentration model and Hoch- Arpshofen model shows that local composition models are more convenient and credible. In conclusion, local composition models are good methods for the estimation of the thermodynamic properties of liquid alloys not because of their convenience and credibility but because of their extensive strong adaptation ability, however, the application of local composition models are strongly dependent on binary liquid alloys and are limited in the narrow temperature range.