Fatigue Deformation of Polycrystalline Cu Using Molecular Dynamics Simulations

TL;DR

This study uses molecular dynamics simulations to explore how polycrystalline copper deforms under cyclic fatigue, revealing dislocation slip and grain boundary migration as key mechanisms.

Contribution

It provides new insights into the atomic-scale deformation mechanisms of polycrystalline copper under fatigue loading through detailed MD simulations.

Findings

Dislocation slip dominates cyclic deformation behavior.

Grain boundary migration leads to grain coarsening after multiple cycles.

Cyclic stress-strain behavior correlates with dislocation density changes.

Abstract

Molecular dynamics (MD) simulations have been performed to investigate the fatigue deformation behaviour of polycrystalline Cu with grain size of 5.4 nm. The samples were prepared using Voronoi algorithm with random grain orientations. Fatigue simulations were carried out by employing fully reversed, total strain controlled cyclic loading at strain amplitude of $\pm4$\% for 10 cycles. The MD simulation results indicated that the deformation behaviour under cyclic loading is dominated by the slip of partial dislocations enclosing the stacking faults. At higher number of cycles, the grain boundary migration leading to coarsening of larger grains at the expense of the smaller grains has been observed. The cyclic stress-strain behaviour, the deformation mechanisms and the variation of dislocation density as a function of cyclic deformation have been discussed.