Effects of atomic bonding nature and size mismatch on thermal stability and glass-forming ability of bulk metallic glasses

Two mathematical models used for quantitatively measuring the effects of atomic bonding nature and atomic size ratios among constituent elements on thermal stability of Mg-based bulk metallic glasses (BMGs) have been proposed recently. In this paper, these models are extended to other BMG systems, and the reliability and feasibility of these models for assessing glass-forming ability (GFA) and the thermal stability of BMGs are carefully examined. It was found that these models are not suitable for evaluating the thermal stability of BMGs in other alloy systems. Instead, a weak correlation between the parameters calculated based on these models (i.e., the electronegativity difference Δx and the atomic size difference δ) and the GFA of BMGs is observed. Our analyses indicate that these two models only partially reflect the effects of the atomic bonding nature and the atomic size ratios on the GFA and need to be further refined.