title: Plasticity of Cu nanoparticles: Dislocation-dendrite-induced strain hardening and a limit for displacive plasticity.
abstract: The plastic behaviour of individual Cu crystallites under nanoextrusion is studied by molecular dynamics simulations. Single-crystal Cu fcc nanoparticles are embedded in a spherical force field mimicking the effect of a contracting carbon shell, inducing pressure on the system in the range of gigapascals. The material is extruded from a hole of 1.1-1.6 nm radius under athermal conditions. Simultaneous nucleation of partial dislocations at the extrusion orifice leads to the formation of dislocation dendrites in the particle causing strain hardening and high flow stress of the material. As the extrusion orifice radius is reduced below 1.3 Å we observe a transition from displacive plasticity to solid-state amorphisation.
authors.affiliation: Technische Universität Darmstadt, Institut für Materialwissenschaft, Fachgebiet Materialmodellierung, Petersenstr. 32, 64287 Darmstadt, Germany ; Department of Physics, FIN-0014 University of Helsinki, PO Box 43, Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Tolvanen
authors.forename: Karsten
authors.initials: K
authors.lastname: Albe
keywords: dislocation interactions; mechanical properties; molecular dynamics; nanoparticle; simulation