Thermodynamic and topological instability approaches for forecasting glass-forming ability in the ternary Al–Ni–Y system

A thermodynamic approach to predict bulk glass-forming compositions in binary metallic systems was recently proposed. In this approach, the parameter γ* = ΔHamor/(ΔHinter − ΔHamor) indicates the glass-forming ability (GFA) from the standpoint of the driving force to form different competing phases, and ΔHamor and ΔHinter are the enthalpies for glass and intermetallic formation, respectively. Good glass-forming compositions should have a large negative enthalpy for glass formation and a very small difference for intermetallic formation, thus making the glassy phase easily reachable even under low cooling rates. The γ* parameter showed a good correlation with GFA experimental data in the Ni–Nb binary system. In this work, a simple extension of the γ* parameter is applied in the ternary Al–Ni–Y system. The calculated γ* isocontours in the ternary diagram are compared with experimental results of glass formation in that system. Despite some misfitting, the best glass formers are found quite close to the highest γ* values, leading to the conclusion that this thermodynamic approach can be extended to ternary systems, serving as a useful tool for the development of new glass-forming compositions. Finally the thermodynamic approach is compared with the topological instability criteria used to predict the thermal behavior of glassy Al alloys.