Interface mediated mechanisms of plastic strain recovery in a AgCu alloy

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.