Model Of Formation Enthalpy For Binary System And Its Application To Thermodynamic Calculation Of Aluminum Alloy

The model of formation enthalpy for binary alloy is basis of the prediction of the thermodynamic parameters. It is important to the metallurgical and forming process of alloys, the multi-scale simulation of microstructural evolution as well as the development of new materials. The study of the thermodynamic properties of aluminum alloy has attracted much attention by researchers all over the world because of such outstanding properties as low density, high specific strength and corrosion resistance, etc. It has become one of the most important materials for human being.This paper studied the formation enthalpy of the results obtained by former researchers. The influence of element size, electronegativity, electron density and other factors on the formation enthalpy of binary alloy was analyzed in detail. The problem in the prediction of formation enthalpy by using Miedema theory was drawn, and the method for further improvement was proposed. It is found from Miedema's work that Miedema model only applies to the small difference in the size of atoms. Therefore, it is possible to correct the influence of the size to improve the prediction accuracy. In view of the problem existing in Miedema model, the calculated results are divided into partial and non-biased type, and the correction can lead to the result larger or smaller for the partial type according to the element size, electronegativity, electron density of the component. On the basis of these corrections, a new model was established for binary alloys. The predicted results are consistent with the experimental results.This paper also calculated thermodynamic parameters, such as the excess entropy, free energy, activity, etc. for binary alloy by using established model of formation enthalpy. The results accord with the experimental results.