A molecular dynamics simulation study on Bauschinger’s effect in nano-scaled Cu systems with and without interfaces

Abstract

Employing the molecular dynamics simulation method, we investigated the responses of nano-scaled Cu systems, including single crystal(SC), and crystals with twin boundaries(TW) and grain boundaries(GB) to cyclic deformation in different strain ranges. Bauschinger’s effect occurring during the cyclic processes was quantified, which showed a decreasing trend in the sequence of SC, GB and TW. The simulation results show that in the nano-scaled systems the annihilation of partial dislocations with opposite signs and shrinkage of associated stacking faults could be more responsible for the Bauchinger’s effect due to the narrowed spacing between boundaries, which may confine reversible movement of generated dislocations. The suggestion is supported by changes in some crucial parameters during cyclic loading processes, such as fluctuations of absorbed strain energy, variations in the amount of defect atoms, failure strains and stress concentrations before fracture. Efforts are made to elucidate possible mechanisms responsible for the observed phenomena.