title: Pseudo Hall-Petch strength reduction in polycrystalline graphene.
abstract: The fracture of polycrystalline graphene is explored by performing molecular dynamics simulations with realistic finite-grain-size models, emphasizing the role of grain boundary ends and junctions. The simulations reveal a ~50% or more strength reduction due to the presence of the network of boundaries between polygonal grains, with cracks preferentially starting at the junctions. With a larger grain size, a surprising systematic decrease of tensile strength and failure strain is observed, while the elastic modulus rises. The observed crack localization and strength behavior are well-explained by a dislocation-pileup model, reminiscent of the Hall-Petch effect but coming from different underlying physics.
authors.affiliation: Department of Engineering Mechanics and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Zhigong
authors.initials: Z
authors.lastname: Song
authors.forename: Vasilii I
authors.initials: VI
authors.lastname: Artyukhov
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Xu
mesh_terms: D003198:Computer Simulation; D055119:Elastic Modulus; D006108:Graphite / Q000737:chemistry*; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D053758:Nanoparticles / Q000737:chemistry*; D049329:Nanostructures; D010316:Particle Size; D013499:Surface Properties
chemical_list: D006108:Graphite