Non-Model Calculation of Fusion Diagrams for Quasi-Simple Systems from Data on Binary Subsystems

Abstract A non-model algorithm for the calculation of fusion diagrams of multicomponent quasi-simple systems from the fusion diagrams of their binary subsystems is presented. The geometric calculation algorithm comprises the solution of sets of linear equations of liquidus isotherms. The thermodynamic calculation algorithm requires only the coordinates of binary eutectics to be known. An exemplary application of both algorithms is shown for the fusion diagrams of ternary quasi-simple salt systems with a common cation or a common anion. The results of calculations by both algorithms and the results of non-model calculations all agree with the available experimental data. All invariant points of various quasi-simple ternary systems (with one different and two identical components) are proved to belong to one monovariant curve, and sets of equations for calculating this curve are presented. Exemplary calculations of monovariant curves are presented, and there is agreement between the non-model calculations and the experimental data on the compositions of ternary invariant points. A set of transcendental equations is compiled to calculate ternary eutectic temperatures from the binary eutectics of quasi-simple subsystems. A thermodynamic method is proposed to determine whether a multicomponent system belongs to the class of quasi-simple systems based on the coordinates of binary eutectics.