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Boron; Cobalt; Fracture; Fracture toughness; Glass; High resolution transmission electron microscopy; Lamellar structures; Metallic glass; Probes; Tantalum; Transmission electron microscopy, Atom probe tomography; Compositional variation; Future designs; Glass microstructure; Hybridization; Mechanical performance; Metallic glass thin films; Thin film metallic glass, Thin films
Abstract:
We report the enhancement of fracture toughness and strength of a cobalt‑tantalum-based metallic glass thin film with increasing boron content. The improvement of the mechanical performance is attributed to the formation of a compositionally lamellar compared to uniform glass microstructure, which becomes thinner with increasing boron content as revealed by transmission electron microscopy. Compositional variations across the lamellar structure are revealed by atom probe tomography. Cobalt- and boron-rich regions alternate sequentially, whereas tantalum exhibits slight variations across the lamellae. Our results can be utilized in future design efforts for metallic glass thin films with outstanding mechanical performance. © 2018 Acta Materialia Inc.