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

TL;DR

This study uses molecular dynamics simulations to explore how size, temperature, and strain rate influence dislocation density and deformation mechanisms in copper nanowires, revealing size and temperature-dependent dislocation behaviors.

Contribution

It provides new insights into the combined effects of size, temperature, and strain rate on dislocation dynamics in Cu nanowires through detailed MD simulations.

Findings

Dislocation density shows two stages: exhaustion and starvation.

Decreasing size and increasing temperature accelerate dislocation exhaustion.

Higher strain rates delay dislocation exhaustion and increase transition strain.

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 $5 \times 10^7$ - $1 \times 10^9$ s$^{-1}$ have been considered. For all the conditions, the variations in dislocation density $(\rho)$ 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.