Interface mediated mechanisms of plastic strain recovery in AgCu alloy

TL;DR

This study combines microscopy and molecular dynamics simulations to reveal how interface structures in AgCu alloys influence plastic strain recovery, highlighting the role of incoherent twin interfaces in driving dislocation retraction and interface rearrangement.

Contribution

It uncovers the specific role of incoherent twin interfaces in facilitating plastic strain recovery in AgCu alloys, a novel insight into interface-mediated deformation mechanisms.

Findings

Incoherent twin interfaces change after loading, driving strain recovery.

Dislocation retraction and interface rearrangement are key to recovery.

Cube-on-cube interfaces show less or no recovery, especially in thicker layers.

Abstract

Through the combination of transmission electron microscopy analysis of the deformed microstructure and molecular dynamics computer simulations of the deformation processes, the mechanisms of plastic strain recovery in bulk AgCu eutectic with either incoherent twin or cube-on-cube interfaces between the Ag and Cu layers and a bilayer thickness of 500 nm have been revealed. The character of the incoherent twin interfaces changed uniquely after dynamic compressive loading for samples that exhibited plastic strain recovery and was found to drive the recovery, which is due to dislocation retraction and rearrangement of the interfaces. The magnitude of the recovery decreased with increasing strain as dislocation tangles and dislocation cell structures formed. No change in the orientation relationship was found at cube-on-cube interfaces and these exhibited a lesser amount of plastic strain recovery in the simulations and none experimentally in samples with larger layer thicknesses with predominantly cube-on-cube interfaces. Molecular dynamics computer simulations verified the importance of the change in the incoherent twin interface structure as the driving force for dislocation annihilation at the interfaces and the plastic strain recovery.