Relation between excess volume, excess free energy and isothermal compressibility in liquid alloys

Abstract Excess volume data of 32 liquid alloys were reviewed and plotted versus their excess free energies. It is hereby found that all combinations of the signs of EV and EG are possible. The excess volume data split into two different curves which are monotonous in EG. For one of these curves the signs of EV and EG are equal and they are opposite for the other. We improved our previously developed model and found that there is an unspecified sign s which can be chosen arbitrarily either + or −. This leads to a split of the predicted curves into two separate ones corresponding to the experimental finding. The model relates excess volume, excess free energy and isothermal compressibility with each other whereas the concept of excess internal pressure is used. The model predicts the excess volume as function of the excess free energy, when reasonable assumptions are made for s and the effective isothermal compressibility. In the present work, the latter has been estimated as an average from the isothermal compressibility values over the involved pure elements. Good qualitative and quantitative agreement with the experimental data is obtained for the systems investigated. The model is valid for at least for −3RT