Glass forming ability in Cu-Zr binary alloy: Effect of nucleation mode

In the present work, thermodynamic and kinetic calculations were combined to study the glass forming ability of Cu-Zr binary system. Applying thermodynamic association model, the primarily crystallized phase and its corresponding driving force can be determined firstly. Then, the whole Time-Temperature-Transformation (TTT) diagrams basing on homogeneous and heterogeneous nucleation modes have been constructed quantitatively. As for the former case, the critical cooling rate is underestimated by about three orders of magnitude in comparison with the experimental observation. As for the latter case adopting suitable values of catalytic factor f(θ) and potential nuclei N₁, the predictions agree well with the experimental results, and moreover, the nose temperature of TTT diagram is upper-shifted. This has been discussed using a competition of the atomic mobility and the reduced nucleation barrier, as well as its further effect on the nucleation and growth process.