Calculation of glass forming ranges in the ternary Y–Cu–Al system and its sub-binaries based on geometric and Miedemaʹs models

A method based on the semi-empirical Miedemaʹs and geometric models was used for the first time to calculate glass forming abilities (GFA) and the glass forming ranges in a ternary system and its sub-binaries. This work incorporates calculations of the formation enthalpies of amorphous alloys and their crystalline (solid solution) counterparts, as well as differences between them for the Y–Cu–Al system. Results indicate that compositions close to Y–Al and Y–Cu sub-binaries exhibit the highest GFA values. In addition, from the normalized entropy change Sσ/kB, the highest GFA was predicted for sub-binaries close to Y–Cu. In both cases, Y atoms play an important role, due to their large atomic radii and highly negative interfacial enthalpies with other constituents. The glass forming ability parameter ΔPHS (which includes both the enthalpy and entropy changes) indicates the range with the highest GFA in the vicinity of the Y40Cu31Al29 alloy composition. The predicted values are in a good agreement with experimental ones as well as with other theoretical results.