A dislocation wake that formed along the fracture surfaces of a mode-I crack, which was introduced at the ductile-brittle transition temperature, was examined by using transmission electron microscopy. Many dislocation loops nucleated at, and near to, the fracture surfaces. Many point defects were also produced during the propagation of a mode-I crack under these conditions. It was noted that the equilibrium concentration of interstitials increased gradually as the crack tip approached, and then decreased suddenly when it passed. Nothing happened at low temperatures because the actual interstitial concentration could not reflect the equilibrium value. At high temperatures, the actual interstitial concentration could increase to such an extent that the interstitials were supersaturated after the crack had passed. Some of these interstitials then precipitated as dislocation loops, thus giving rise to the dislocation wake. The dislocation loops which formed could act as sources of glide dislocations under the high stresses near to a crack tip. At the same time, the supersaturated point defects which had not precipitated then interacted with moving dislocations so as to retard their motion.

On the nature of a dislocation wake along a crack introduced into Si at the ductile-brittle transition temperature Suprijadi, H.Saka: Philosophical Magazine Letters, 1998, 78[6], 435-43