title: A maximum in the strength of nanocrystalline copper.
abstract: We used molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15 nanometers. This maximum is because of a shift in the microscopic deformation mechanism from dislocation-mediated plasticity in the coarse-grained material to grain boundary sliding in the nanocrystalline region. The simulations allow us to observe the mechanisms behind the grain-size dependence of the strength of polycrystalline metals.
authors.affiliation: Center for Atomic-Scale Materials Physics (CAMP), Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark. schiotz@fysik.dtu.dk
authors.forename: Jakob
authors.initials: J
authors.lastname: Schiøtz
authors.forename: Karsten W
authors.initials: KW
authors.lastname: Jacobsen