Molecular Dynamics Simulations of Dislocation Activity in Single-Crystal and Nanocrystalline Copper Doped with Antimony |
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Authors: | Rahul K Rajgarhia Douglas E Spearot Ashok Saxena |
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Affiliation: | (1) Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701, USA;(2) Present address: Boston Scientific, Saint Paul, MN 55112, USA; |
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Abstract: | Recent experimental and simulation results have indicated that high-temperature grain growth in nanocrystalline (NC) materials
can be suppressed by introducing dopant atoms at the grain boundaries. However, the influence of grain boundary dopants on
the mechanical behavior of stabilized NC materials is less clear. In this work, molecular dynamics (MD) simulations are used
to study the impact of very low dopant concentrations (<1.0 at. pct Sb) on plastic deformation in single-crystal and NC Cu.
A new interatomic potential for low Sb concentration Cu-Sb solid-solution alloys is used to model dopant/host and dopant/dopant
interatomic interactions within the MD framework. In single-crystal models, the strained regions around the Sb atoms act as
heterogeneous sources for partial dislocation nucleation; the stress associated with this process decreases with increasing
Sb concentration. In NC models, MD simulations indicate that Sb dopants randomly dispersed at the grain boundaries cause an
increase in the flow stress in NC Cu, implying that Sb atoms at the grain boundaries retard both grain boundary sliding and
dislocation nucleation from grain boundary regions. |
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