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Title: Quantitative description of plastic deformation in nanocrystalline Cu: Dislocation glide versus grain boundary sliding

Abstract

Uniaxial plastic deformation of polycrystalline Cu with grain sizes in the range of 5-20 nm was studied by using molecular dynamics computer simulations. We developed a quantitative analysis of plasticity by using localized slip vectors to separate the contributions of dislocation activity from grain boundary sliding. We conclude that the competition between these two mechanisms depends on strain rate and grain size, with the dislocation activity increasing with grain size but decreasing with increasing strain rate. For samples with a 5 nm grain size, dislocations contribute {approx_equal}50% of the total plastic strain during steady state deformation at a rate of 1x10{sup 8} s{sup -1}, but this fraction decreases to 35% at a rate of 1x10{sup 10} s{sup -1}. When the grain size is increased to 20 nm, dislocations account for 90% of the strain, even at 1x10{sup 10} s{sup -1}. During the initial stages of plastic deformation, grain boundary sliding initially decreases with strain owing to strain-induced relaxation processes within the grain boundaries. The grains also rotate a few degrees during straining to 20%; the rate of rotation (per unit strain) slightly decreases with strain rate. Lastly, we computed the amount of forced atomic mixing during plastic deformation. The meanmore » square separation distance between atom pairs within grain interiors increases with strain at a rate proportional to their distance apart (i.e., the mixing is superdiffusive), but for pair separations greater than the grain size, this rate becomes independent of the separation distance.« less

Authors:
; ; ;  [1];  [2]
  1. Department of Materials Science and Engineering, University of Illinois, Urbana Champaign, Urbana, Illinois 61801 (United States)
  2. Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Publication Date:
OSTI Identifier:
21143265
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 77; Journal Issue: 13; Other Information: DOI: 10.1103/PhysRevB.77.134108; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ATOMS; COMPETITION; COMPUTERIZED SIMULATION; COPPER; DEFORMATION; DISLOCATIONS; GRAIN BOUNDARIES; GRAIN SIZE; MIXING; MOLECULAR DYNAMICS METHOD; NANOSTRUCTURES; PLASTICITY; PLASTICS; POLYCRYSTALS; ROTATION; SLIP; STEADY-STATE CONDITIONS; STRAIN RATE; STRAINS; STRESS RELAXATION

Citation Formats

Vo, N Q, Averback, R S, Bellon, P, Odunuga, S, and Caro, A. Quantitative description of plastic deformation in nanocrystalline Cu: Dislocation glide versus grain boundary sliding. United States: N. p., 2008. Web. doi:10.1103/PHYSREVB.77.134108.
Vo, N Q, Averback, R S, Bellon, P, Odunuga, S, & Caro, A. Quantitative description of plastic deformation in nanocrystalline Cu: Dislocation glide versus grain boundary sliding. United States. doi:10.1103/PHYSREVB.77.134108.
Vo, N Q, Averback, R S, Bellon, P, Odunuga, S, and Caro, A. Tue . "Quantitative description of plastic deformation in nanocrystalline Cu: Dislocation glide versus grain boundary sliding". United States. doi:10.1103/PHYSREVB.77.134108.
@article{osti_21143265,
title = {Quantitative description of plastic deformation in nanocrystalline Cu: Dislocation glide versus grain boundary sliding},
author = {Vo, N Q and Averback, R S and Bellon, P and Odunuga, S and Caro, A},
abstractNote = {Uniaxial plastic deformation of polycrystalline Cu with grain sizes in the range of 5-20 nm was studied by using molecular dynamics computer simulations. We developed a quantitative analysis of plasticity by using localized slip vectors to separate the contributions of dislocation activity from grain boundary sliding. We conclude that the competition between these two mechanisms depends on strain rate and grain size, with the dislocation activity increasing with grain size but decreasing with increasing strain rate. For samples with a 5 nm grain size, dislocations contribute {approx_equal}50% of the total plastic strain during steady state deformation at a rate of 1x10{sup 8} s{sup -1}, but this fraction decreases to 35% at a rate of 1x10{sup 10} s{sup -1}. When the grain size is increased to 20 nm, dislocations account for 90% of the strain, even at 1x10{sup 10} s{sup -1}. During the initial stages of plastic deformation, grain boundary sliding initially decreases with strain owing to strain-induced relaxation processes within the grain boundaries. The grains also rotate a few degrees during straining to 20%; the rate of rotation (per unit strain) slightly decreases with strain rate. Lastly, we computed the amount of forced atomic mixing during plastic deformation. The mean square separation distance between atom pairs within grain interiors increases with strain at a rate proportional to their distance apart (i.e., the mixing is superdiffusive), but for pair separations greater than the grain size, this rate becomes independent of the separation distance.},
doi = {10.1103/PHYSREVB.77.134108},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 13,
volume = 77,
place = {United States},
year = {2008},
month = {4}
}