Effect of size, temperature and strain rate on dislocation density and deformation mechanisms in Cu nanowires

Abstract

In the present study, molecular dynamics (MD) simulations have been performed to understand the effect of nanowire size, temperature and strain rate on the variations in dislocation density and deformation mechanisms in <100> Cu nanowires. The nanowire size has been varied in the range 1.446-43.38 nm with a constant length of 21.69 nm. Different temperatures varying from 10 K to 700 K and strain rates in the range of 5 × 10 7 -1 × 10 9 s −1 have been considered. For all the conditions, the variations in dislocation density (ρ) has been calculated as a function of strain. The results indicate that the variations in dislocation density exhibits two stages irrespective of the conditions: (i) dislocation exhaustion at small strains followed by (ii) dislocation starvation at high strains. However, with decreasing size and increasing temperature, the rate of dislocation exhaustion increases, which results in early transition from dislocation exhaustion stage to dislocation starvation stage. Similarly, with increasing strain rate, the rate of dislocation exhaustion and also the transition strain increases.

Effect of crystal orientation on the size effects of nano-scale fcc metals

“…Yaghoobi and Voyiadjis [64] MD simulations on the Ni nanopillars showed that the deformation dominant mechanism is independent of the strain value and is affected only by the pillar size. Rohith et al's [68] MD simulation on the tensile behaviour of Cu nanowires showed two stages irrespective of deformation temperature and strain rates; dislocation exhaustion at early stages of deformation followed by dislocation starvation at high strains. Korchuganov et al [69] proposed an atomic model for the nucleation of dislocation and twins based on the local reversible fcc → bcc → fcc transformation.…”

Pencil‐Shaped Necking of Thick Al Whisker Grown by Stress‐Induced Migration and Enhancement of Tensile Strength

“…New grains readily formed from the subgrains of the dislocation networks at their expense. [35,36] The reduction in the whisker diameter and obstruction of nucleated dislocations from escaping to the surface by the newly formed grains are considered to both maintain the recrystallization process and increase the tensile strength of the tested whisker. If the required stress concentration is not maintained (e.g., by decreasing the strain rate), the strengthening cycle is terminated.…”

Effect of oxidation on mechanical properties of copper nanowire: A ReaxFF (reactive force field) molecular dynamics study

“…In recent years, [001]-oriented Cu NWs have garnered attention for their unique mechanical, electrical, optical, catalytic, and thermal properties. [1][2][3][4][5][6][7][8]11,39,43 However, their performance depends on the pre-existing native oxide shell layer on their free surfaces. Therefore, our research focuses solely on [001]-oriented Cu NWs under tensile loading.…”