title: Microstructure versus flaw: mechanisms of failure and strength in nanostructures.
abstract: Understanding failure in nanomaterials is critical for the design of reliable structural materials and small-scale devices with nanoscale components. No consensus exists on the effect of flaws on fracture at the nanoscale, but proposed theories include nanoscale flaw tolerance and maintaining macroscopic fracture relationships at the nanoscale with scarce experimental support. We explore fracture in nanomaterials using nanocrystalline Pt nanocylinders with prefabricated surface notches created using a "paused" electroplating method. In situ scanning electron microscopy (SEM) tension tests demonstrate that the majority of these samples failed at the notches, but that tensile failure strength is independent of whether failure occurred at or away from the flaw. Molecular dynamics simulations verify these findings and show that local plasticity is able to reduce stress concentration ahead of the notch to levels comparable with the strengths of microstructural features (e.g., grain boundaries). Thus, failure occurs at the stress concentration with the highest local stress whether this is at the notch or a microstructural feature.
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: 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
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D056004:Molecular Dynamics Simulation; D053758:Nanoparticles / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials