An experimental observation of dislocation nucleation based on the Peierls concept

The HREM-moiré method developed by Dai and Xing [1] is an experimental technique which allows for the direct measurement of such parameters as displacement, strain and dislocation in the nanoscopic range. This technique was used to measure the nanoscopic deformation field near the tip of a quasi-cleavage crack in silicon. A process of dislocation nucleation was observed. A long dislocation extending about 600 burgers vectors was found at the crack tip and the slip distribution along it was measured. This distributed dislocation has a similar slip structure to the one based on the Peierls concept described by Rice [2], but has a much longer slip range. The nanoscopic strain distribution near the crack tip was obtained. There is a strain field controlled by linear elastic fracture mechanics at the very vicinity of the crack tip.