In order to clarify the shear instability condition of a local field, which led to dislocation nucleation, molecular dynamics simulations were made of a Ni nanowire in tension. It was found that a partial dislocation nucleated from the wire edge at a strain of 0.093 to 0.096. The dislocation nucleation site was different in each simulation, due to statistical fluctuations. Strain concentration was observed in a ¼-sphere (3nm-radius), centred on the nucleation site, before the dislocation appeared. Detailed observations revealed that the dislocation nucleated when the strain distribution in the region exceeded a critical value. The local strain concentration disappeared when the strain distribution was lower than the critical value. The strain distribution caused dislocation nucleation when the number of unstable lattices was greater than 0.1/s.
Criterion on Local Instability for Dislocation Nucleation in Nickel Crystal. L.T.Kitamura, Y.Umeno, S.Noda: Journal of the Society of Materials Science, Japan, 2000, 49, 527-33