Irradiation-initiated plastic deformation in prestrained single-crystal copper

With large-scale molecular dynamics simulations, we investigate the response of elastically prestrained single-crystal Cu to irradiation as regards the effects of prestrain magnitude and direction, as well as PICA (primary knock-on atom) energy. Under uniaxial tension, irradiation induces such defects as Frenkel pairs, stacking faults, twins, dislocations, and voids. Given the high dislocation concentration, twins and quad-stacking faults form through overlapping of different stacking faults. Voids nucleate via liquid cavitation, and dislocations around void play a lesser role in the void nucleation and growth. Dislocation density increases with increasing prestrain and PICA energy. At a given prestrain, there exists a critical PICA energy for dislocation activation, which decreases with increasing prestrain and depends on crystallographic direction of the applied prestrain. (C) 2015 Elsevier B.V. All rights reserved.