A fivefold-related volume descriptor for evaluating glass-forming ability and screening compositions in metallic glasses

Metallic glasses have attractive engineering potential, but their development is still limited by narrow compositional windows and trial-and-error alloy design. For complex metallic alloys, establishing structural criteria to distinguish glass-forming ability (GFA) among compositions remains challenging. In this work, Ni-Zr-Ta candidate alloys designed using a cluster-based composition approach combined with a mixing-entropy criterion were studied by molecular dynamics simulations and experimental validation to examine the relationship between atomic structure and GFA variation. The results show that single structural indicators are insufficient to distinguish the relative GFA among compositions. Instead, GFA variation is more closely related to the coupled evolution of fivefold structure enrichment, spatial connectivity, and local densification. These features were integrated into a fivefold-related volume-topology descriptor (N5-VT) to evaluate GFA-related structural differences by combining enrichment, connectivity, and densification. The predicted GFA ranking agrees with X-ray diffraction (XRD), differential scanning calorimetry (DSC), and critical diameter measurements, with Ni 58.42 Zr 18.73 Ta 22.85 (NZA2) showing the highest GFA. NZA2 exhibits greater fivefold-structure enrichment, stronger spatial connectivity, and more favorable local densification. Although the simulated structures cannot reproduce all experimental details, they capture the relative structural differences among compositions. Similar trends in representative binary, ternary, and quaternary metallic glasses suggest potential transferability. This work provides a structure-based route for evaluating and pre-screening high-GFA metallic glasses.