Theoretical Investigation of Thermodynamic Properties of the Al-Si-Fe Ternary Alloy.

Abstract

Aiming at the current lack of thermodynamic parameters related to the preparation of aluminum-silicon-iron alloys from spent refractory materials in aluminum electrolytic cells, the Miedema model was used to calculate the thermodynamic parameters of Al-Si, Al-Fe, and Si-Fe binary alloys. On this basis, the Toop model was combined to calculate the mixing enthalpy ΔH, excess entropy SE, excess Gibbs free energy GE, and component activity α of Al-Si-Fe ternary alloys. The results show that ΔH, SE, and GE of binary alloys are all negative values. The properties of the Al element and Si element are similar, and they are different from the Fe element. The ternary alloys also have negative values of ΔH, SE, and GE in the alloy composition range, and their values change obviously in the region where the content of Fe is high or low. The activity values of all components decrease dramatically along with the diminishing of the corresponding molar fractions, and the activity values of Al, Si, and Fe are smaller in the central portion of the triangle of ternary components. It indicates that there is a strong interaction between the three elements, which easily forms ternary intermetallic compounds.