Research On The Application Of The Molecular Interaction Volume Model In The Cu-based Liquid Alloy Systems

In this thesis, the thermodynamic properties of 22 binary Cu-based liquid alloys have been predicted by the molecular interaction volume model (MIVM). The results show that the prediction effect of MIVM is acceptable in both the positive deviation systems and the negative deviation ones, relatively, the former is better than the later. As to the coexisted deviation systems, the results given by MIVM are inadequate. At the same time, when one calculates the parameters Bij and Bji of the negative deviationsystem, the regions in which there are three pairs of roots have been given. It has been indicated that it is safety that the product of Bij Bji is maximum.Then based on the results in binary liquid alloys, the thermodynamic properties of 7 ternary Cu-based liquid alloys and 7 multi-component systems (Cd-Bi-Pb, Cd-Bi-Sn, Cd-Pb-Sn, Cd-Bi-Pb-Sn, Zn-Cd-Pb-Sn, Zn-Cd-Bi-Sn and Zn-Cd-Bi-Pb-Sn) have been predicted and compared by MIVM and the geometrical models. The results show that the predicted values of MIVM and geometrical models are in good agreement with experimental data. A significant feature of MIVM and the geometrical models is its ability to predict the thermodynamic properties of multi-component liquid alloys from the corresponding binaries. However, MIVM need only the corresponding binary infinite dilute activity coefficients, whereas geometrical models have to use some continuous analytical expressions of experimental data of the binaries. And MIVM is suitable to a partial miscible system, but geometrical models cannot be used for it. And MIVM is of a clearer physical meaning than geometrical models. Then a thermodynamic criterion for identifying the symmetry of ternary liquid alloy systems form regular solution is given and is applied to 10 ternary liquid alloy systems. The results show that if we choose a proper old geometrical model in terms of the thermodynamic criterion for identifying the symmetry of real systems, the predicted values of the model is more approximate to experimental data than those of the new general model. Therefore, the thermodynamic criterion is convenient and reliable.Finally, MIVM is applied to predict thermodynamic properties of liquid metal-sulfur solution. The results show that MIVM is not suitable for this kind ofsystems. We think that the failed reason lies in that the molecular interaction energy in MIVM is independent of component concentration. In fact, liquid metal-sulfide solutions are known to exhibit a high degree of short-range ordering, i.e., the molecular interaction energy in liquid metal-sulfide solutions alters with component concentration.