Topological ordering and spatial distribution of atomic clusters in CuZr metallic glasses

Metallic glasses lack long-range order, whereas their local structures and spatial heterogeneity strongly influence their physical properties. In this study, the local atomic structures and spatial heterogeneity in Cu Zr metallic glasses were analyzed using a topological method based on cluster homology analysis. Structural models of Cu x Zr 100−x (x = 30–70) alloys were constructed by molecular dynamics simulations, and second-order persistence diagrams (PD2) were generated for first-nearest-neighbor atomic clusters. As a result, it was clarified that with increasing Cu composition, the mean value of Birth decreases while its variance increases. This indicates that although the cluster size decreases, the topological diversity increases. The distribution of Birth basically follows a normal distribution, whereas in Cu-rich compositions, isotropic and densely packed clusters represented by icosahedra were found to form a shoulder in the distribution. These atomic clusters were shown to be spatially localized and interconnected, forming superclusters. The shoulder-like deviation of the Birth distribution suggests that the local structures in Cu-rich alloys have distinctive topological characteristics.