Using atomistic simulations, the nucleation and emission of dislocations from face-centered cubic/body-centered cubic incoherent interfaces in which interface dislocations had only in-plane Burgers vectors was studied. It was shown that nucleation sites and preferred slip systems were associated with interface regions having intense localized shear and were not solely determined by Schmid factors. Activation barriers for nucleation from the interface were lower than those for homogeneous nucleation, indicating that flat fcc/bcc incoherent interfaces could act as viable sources of lattice dislocations. The expansion process within the interface involved a series of pinning and de-pinning events at periodically occurring points. The pinning points in this case corresponded to core spreading at the vortical displacement region; occurring at a spacing of 1.2nm. Consequently, loop expansion into the Cu crystal proceeded in discrete jumps. Consequently, the stress–energy curve associated with interfacial dislocation emission also exhibited periodic jumps. Thus the atomic-scale study had revealed that the nucleation sites and the activated slip system for flat, incoherent fcc/bcc interface were found to corresponded to regions having the most intense interface distortions, and were not determined solely by the crystallographic Schmid factor.

Dislocation Nucleation Mechanisms From FCC/BCC Incoherent Interfaces. R.F.Zhang, J.Wang, I.J.Beyerlein, T.C.Germann: Scripta Materialia, 2011, 65[11], 1022-5