Deformation-induced defects were studied by means of positron lifetime measurements. Two lifetime components, which were related to dislocations and to large vacancy clusters, were detected after deformation. Annealing experiments showed that the dislocation-related component consisted of 2 further components. One annihilated during annealing at about 900C. The other remained even at 1100C. The latter component was attributed to dislocations themselves. The positron trapping rate due to dislocations was proportional to the reciprocal of the temperature, between 100 and 300K, and saturated at temperatures below 50K. This behavior was explained in terms of shallow trapping levels which originated from the dilatational strain field around dislocations and from the 1-dimensional nature of dislocations.

A.Kawasuso, M.Suezawa, M.Hasegawa, S.Yamaguchi, K.Sumino: Materials Science Forum, 1995, 196-201, 1177-82