It was demonstrated that activation pathways for dislocation-loop nucleation from crack tips could be explored in full atomistic detail by using a form of the nudged elastic band method. The approach was demonstrated in detail by the example of edge emission from an Fe crack under mode-II loading, in which activation-energy barriers were obtained as a function of the sub-critical stress intensity, and the energy barriers for loop formation were compared with 2-dimensional calculations. Activation energy barriers were also computed for an intrinsically ductile crack-tip orientation under mode-I loading. From this, it was possible to deduce the frequency of nucleation from the crack tip.

Atomistic Simulation of Dislocation Nucleation Barriers from Crack-Tips in α-Fe. P.A.Gordon, T.Neeraj, M.J.Luton: Modelling and Simulation in Materials Science and Engineering, 2008, 16[4], 045006 (13pp)