Classical molecular dynamics simulations were used to examine the strain-rate sensitivity of single-crystalline and twinned Au nanowires (NWs) with a diameter of 12.3 nm deformed in tension at temperatures between 10K and 450K. It was found that the strain-rate sensitivity above 100K was significantly smaller in twinned Au NWs with perfectly circular cross-section than in similar NWs without twins, while the activation volume remains in the same range of 1b3–15b3 with b the magnitude of Burgers vector. This behavior was markedly different from that generally observed in bulk face-centered cubic metals where addition of nanoscale twins increases both strength and strain-rate sensitivity. Furthermore, the simulations revealed a threefold decrease in strain-rate sensitivity in twinned Au NWs with zig-zag morphology constructed by assembly of {111} surface facets, in comparison to the different types of circular Au NWs. The rate-controlling deformation mechanisms related to surface dislocation emission and twin-slip interaction, and their dependence on temperature and surface morphology were analyzed in detail. The combination of ultrahigh strength and decreased sensitivity to strain-rate predicted above 100K in twinned Au NWs with faceted surface morphology holds great promise for creating metallic nanostructures with increased failure resistance to extreme loading conditions

Effects of Twin and Surface Facet on Strain-Rate Sensitivity of Gold Nanowires at Different Temperatures. C.Deng, F.Sansoz: Physical Review B, 2010, 81[15], 155430