Evaluation of glass forming ability of Zr–Nb alloy systems through liquid fragility and Voronoi cluster analysis

Abstract

In the present study, a molecular dynamics (MD) simulation-based investigation has been carried out for Zr-Nb binary system to analyze structural evolution during the glass formation along with its underlying physics for identifying suitable composition having better glass forming ability (GFA). The analysis is performed through the determination of liquid fragility, coordination numbers, and Voronoi cluster analysis. Results from Angell’s plot have shown that Zr50Nb50 specimen is a strong liquid and has the highest glass forming ability. It is revealed from Voronoi cluster analysis, that Zr50Nb50 metallic glass has a higher population fraction of icosahedral cluster, which also confirms its better glass forming ability. Apart from 〈0 0 12 0〉 icosahedral polyhedra, some Zr-centered clusters like 〈0 1 10 2〉, 〈0 2 8 5〉 and 〈0 2 8 4〉 are also found to be the key factors with respect to slowing down the dynamics of the system during liquid to glass transition. In addition, a pathway for Zr50Nb50 metallic glass formation is presented to show different stages of structural transformation from liquid to glass state.