Columnar atomic arrangements in Zr-Pt metallic glasses and their appearance in high-resolution electron microscopy

Abstract

The characteristics of medium-range order structures in Zr80Pt20 metallic glasses were investigated through molecular dynamics simulations and transmission electron microscopy. Two dominant Pt-centered atomic clusters, icosahedral and icosahedral-like, were found to exhibit distinct spatial distribution characteristics in the simulated models. The icosahedral atomic clusters are connected through interpenetration, as commonly suggested, forming localized medium-range order. In contrast, the icosahedral-like atomic clusters tend to form more extended structures through edge- and face-sharing connections. The latter can be interpreted as interpenetrating when Zr-centered atomic clusters are taken into account. We also show that Zr-centered atomic clusters with relatively higher coordination numbers tend to form interpenetrating structures on a larger scale, compared with Pt-centered atomic clusters. Remarkably bright spots frequently observed in experimental high-resolution electron microscopy images were interpreted as columnar structures formed by atomic clusters aligned along the incident direction of the electron beam.