Triangle Criterion of Glass-Forming Ability and Stability for Metallic Glasses

Based on the glass-forming ability (GFA) during cooling process and the glass stability (GS) of heating process, a triangle to evaluate GFA and GS, namely Tri-FAS, with the combination of pseudo-four characteristic parameters as vertices was established. Accordingly, a GFA&GA criterion (G-FAS) was deduced as G-FAS=T-g/T-l+T-x/T-l+T-x/T-g (T-x is onset crystallization temperature; T-l is liquid temperature; T-g is glass transition temperature). Additionally, the criterion was modified based on the competitive relationship between amorphous phase and crystal phase during cooling process and the contribution of each component to the criterion: G-FAS(m)=T-g/(1.5T(x))+T-x/T-l+T-x/T-g and G-FAS(m)'=T-g/T-l+T-x/T-l+(T-x/T-g)(a) (a approximate to 1.5 +/- 0.2). The correlation between G-FAS and critical cooling rate R-c and that between G-FAS and T-xg (T-xg reflects the supercooled liquid region of glass, T-xg=T-x/T-g) were discussed, which could reflect GFA and GS, respectively. Through the determination results of GFA and GS of abundant metallic glasses and other glass formers, the validity of the proposed G-FAS criterion was evaluated. Results show that with respect to both GFA and GS, the G-FAS criterion is reliable in various glass former systems, showing wide applications. The proposed Tri-FAS and G-FAS criterion can provide guidance during the fabrication and application of metallic glasses.