The dependence of homogeneous dislocation nucleation upon the crystallographic orientation of pure Cu under uniaxial tension and compression was studied. Molecular dynamics simulation results, using an embedded-atom method potential showed that the stress required for homogeneous dislocation nucleation was highly dependent upon the crystallographic orientation and the uniaxial loading conditions. Certain orientations required a higher stress in compression ([110] and [111]), and other orientations required a higher stress in tension ([100]). The resolved shear stress in the slip direction was unable to capture completely the dependence of homogeneous dislocation nucleation upon the crystal orientation and the uniaxial loading conditions.

Tension-Compression Asymmetry in Homogeneous Dislocation Nucleation in Single Crystal Copper. M.A.Tschopp, D.L.McDowell: Applied Physics Letters, 2007, 90[12], 121916