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Title: Material transport via the emission of shear loops during void growth: A molecular dynamics study

Abstract

The growth of a nanovoid in single-crystal copper has been studied via molecular dynamics (MD) method. The objective is to build the correlation between material transport pattern and dislocation structures. MD results are examined by characterizing the material transport via the “relative displacement” of atoms, where the homogenous elastic deformation has been excluded. Through this novel approach, we are able to illustrate the feasibility of void growth induced by shear loops/curves. At a smaller scale, the formation and emission of shear loops/curves contribute to the local mass transport. At a larger scale, a new mechanism of void growth via frustum-like dislocation structure is revealed. A phenomenological description of void growth via frustum-like dislocation structure is also proposed.

Authors:
;  [1]
  1. Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada)
Publication Date:
OSTI Identifier:
22596794
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 119; Journal Issue: 22; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOMS; COPPER; CRYSTAL GROWTH; DEFORMATION; DIAGRAMS; DISLOCATIONS; ELASTICITY; EMISSION; MOLECULAR DYNAMICS METHOD; MONOCRYSTALS; NANOSTRUCTURES; TRANSPORT THEORY

Citation Formats

Cui, Yi, and Chen, Zengtao, E-mail: zengtao.chen@ualberta.ca. Material transport via the emission of shear loops during void growth: A molecular dynamics study. United States: N. p., 2016. Web. doi:10.1063/1.4953089.
Cui, Yi, & Chen, Zengtao, E-mail: zengtao.chen@ualberta.ca. Material transport via the emission of shear loops during void growth: A molecular dynamics study. United States. doi:10.1063/1.4953089.
Cui, Yi, and Chen, Zengtao, E-mail: zengtao.chen@ualberta.ca. 2016. "Material transport via the emission of shear loops during void growth: A molecular dynamics study". United States. doi:10.1063/1.4953089.
@article{osti_22596794,
title = {Material transport via the emission of shear loops during void growth: A molecular dynamics study},
author = {Cui, Yi and Chen, Zengtao, E-mail: zengtao.chen@ualberta.ca},
abstractNote = {The growth of a nanovoid in single-crystal copper has been studied via molecular dynamics (MD) method. The objective is to build the correlation between material transport pattern and dislocation structures. MD results are examined by characterizing the material transport via the “relative displacement” of atoms, where the homogenous elastic deformation has been excluded. Through this novel approach, we are able to illustrate the feasibility of void growth induced by shear loops/curves. At a smaller scale, the formation and emission of shear loops/curves contribute to the local mass transport. At a larger scale, a new mechanism of void growth via frustum-like dislocation structure is revealed. A phenomenological description of void growth via frustum-like dislocation structure is also proposed.},
doi = {10.1063/1.4953089},
journal = {Journal of Applied Physics},
number = 22,
volume = 119,
place = {United States},
year = 2016,
month = 6
}
  • The effect of stress-triaxiality on growth of a void in a three dimensional single-crystal face-centered-cubic (FCC) lattice has been studied. Molecular dynamics (MD) simulations using an embedded-atom (EAM) potential for copper have been performed at room temperature and using strain controlling with high strain rates ranging from 10{sup 7}/sec to 10{sup 10}/sec. Strain-rates of these magnitudes can be studied experimentally, e.g. using shock waves induced by laser ablation. Void growth has been simulated in three different conditions, namely uniaxial, biaxial, and triaxial expansion. The response of the system in the three cases have been compared in terms of the voidmore » growth rate, the detailed void shape evolution, and the stress-strain behavior including the development of plastic strain. Also macroscopic observables as plastic work and porosity have been computed from the atomistic level. The stress thresholds for void growth are found to be comparable with spall strength values determined by dynamic fracture experiments. The conventional macroscopic assumption that the mean plastic strain results from the growth of the void is validated. The evolution of the system in the uniaxial case is found to exhibit four different regimes: elastic expansion; plastic yielding, when the mean stress is nearly constant, but the stress-triaxiality increases rapidly together with exponential growth of the void; saturation of the stress-triaxiality; and finally the failure.« less
  • A molecular-dynamics study is presented of the mechanism and kinetics of void growth and morphological evolution in ductile metallic thin films subject to biaxial tensile strains. The void becomes faceted, grows, and relieves strain by emission from its surface of pairs of screw dislocations with opposite Burgers vectors. Repeated dislocation generation and propagation leads to formation of a step pattern on the film's surfaces. A simple phenomenological kinetic model of void growth is derived. Such kinetic equations can be used to formulate constitutive theories of plastic deformation for continuum-scale modeling of void evolution. (c) 2000 American Institute of Physics.
  • An abstract for this journal article is not available at this time.