title: Mechanisms of failure in nanoscale metallic glass.
abstract: The emergence of size-dependent mechanical strength in nanosized materials is now well-established, but no fundamental understanding of fracture toughness or flaw sensitivity in nanostructures exists. We report the fabrication and in situ fracture testing of ∼70 nm diameter Ni-P metallic glass samples with a structural flaw. Failure occurs at the structural flaw in all cases, and the failure strength of flawed samples was reduced by 40% compared to unflawed samples. We explore deformation and failure mechanisms in a similar nanometallic glass via molecular dynamics simulations, which corroborate sensitivity to flaws and reveal that the structural flaw shifts the failure mechanism from shear banding to cavitation. We find that failure strength and deformation in amorphous nanosolids depend critically on the presence of flaws.
authors.affiliation: Division of Chemistry and Chemical Engineering and ‡Division of Engineering and Applied Science, California Institute of Technology , 1200 E. California Blvd., Pasadena, California 91125, United States.
authors.forename: X Wendy
authors.initials: XW
authors.lastname: Gu
authors.forename: Mehdi
authors.initials: M
authors.lastname: Jafary-Zadeh
authors.forename: David Z
authors.initials: DZ
authors.lastname: Chen
authors.forename: Zhaoxuan
authors.initials: Z
authors.lastname: Wu
authors.forename: Yong-Wei
authors.initials: YW
authors.lastname: Zhang
authors.forename: David J
authors.initials: DJ
authors.lastname: Srolovitz
authors.forename: Julia R
authors.initials: JR
authors.lastname: Greer
keywords: Size effect; flaw sensitivity; fracture; mechanical properties; metallic glass; molecular dynamics; notch sensitivity