Atomistic simulations of dislocation nucleation at copper grain boundaries under uniaxial tension and compression

Atomistic simulations are used to investigate how grain boundary structure influences dislocation nucleation under uniaxial tension and compression for a specific class of (110) symmetric tilt grain boundaries that contain the E structural unit. After obtaining the minimum energy grain boundary structure, molecular dynamics was employed based on an embeddedatom method potential for Cu at 10 K. Simulation results show that higher nucleation stresses are required in uniaxial compression than in tension. Additionally, analysis of the dislocation nucleation mechanisms show several differences between tension and compression. For instance, partial dislocations are nucleated in tension and full dislocations are nucleated in compression. The tension-compression asymmetry in mechanisms and responses can be partially explained by the resolved stress components normal to and on the slip plane on which the dislocation nucleates.