Recent experimental and simulation results have indicated that high-temperature grain growth in nanocrystalline (NC) materials could 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 was less clear. In this work, molecular dynamics simulations were used to study the impact of very low dopant concentrations (<1.0at%Sb) on plastic deformation in single-crystal and NC Cu. A new interatomic potential for low Sb concentration Cu-Sb solid-solution alloys was used to model dopant/host and dopant/dopant interatomic interactions within the molecular dynamics 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, molecular dynamics 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.

Molecular Dynamics Simulations of Dislocation Activity in Single-Crystal and Nanocrystalline Copper Doped with Antimony. R.K.Rajgarhia, D.E.Spearot, A.Saxena: Metallurgical and Materials Transactions A, 2010, 41[4], 854-60