Characteristics of cluster formulas for binary bulk metallic glasses

•A correlation between GFA and cluster formula issued from the cluster-plus-glue-atom model was revealed.•Three characteristics of binary BMG formulas were unveiled, which may guide new BMG design.•Binary eutectics in Cu-(Zr, Hf, Ti), Ni-(Nb, Ta), and Al–Ca systems were accurately interpreted.

Compositions of typical bulk metallic glasses (BMGs) and boron-containing eutectics have been previously interpreted by cluster formulas issued from the cluster-plus-glue-atom model. In the present work, binary BMG composition formulas are established via dissociating dual-cluster formulas for their relevant eutectics. It is unveiled that BMG formulas satisfy three ubiquitous rules: cluster formula of the form [cluster](glue atom)1 or 3 with 24 valence electrons per unit formula, the center and the glue sites occupied by the same atomic species, and the BMG composition falling within the eutectic zone. These characteristics may serve as the finger prints for good glass formers and eventually the BMG design tool.