Calculation of metastable free-energy diagrams and glass formation in the Mg–Cu–Y alloy and its boundary binaries using the Miedema model

We have extended Miedemaʹs model to the modelling of free-energy diagrams in ternary alloys and applied the extended model to obtain a thermodynamic characterization of the glass formation range in Mg–Cu–Y. A structural term has been added in the calculation of the free energy of formation of solid solutions. By assuming that amorphization competes with formation of the hcp and fcc solid solutions, we have evaluated the region of compositions in which the system can be amorphized by quenching or casting of the liquid alloy. Equations of analytical geometry are proposed to search for regions of coexistence of amorphous and solid solutions, which could not be found for this ternary alloy. Heats of glass crystallisation have been calculated. The results of our model are in reasonable agreement with experimental data.