Defects were introduced into 4N-purity sheet samples by means of cold-rolling. Positron annihilation and hardness studies of the annealing response revealed that, at deformations of a few percent, vacancy-type defects were easily produced and reached saturation. Meanwhile, the number of dislocation-related defects increased almost linearly with increasing deformation. The peaks of the recovery and recrystallization stages were at 150 to 200C and at 450 to 500C, respectively. It was found that positron annihilation responded most sensitively to the annealing of vacancy-type defects in the recovery stage, whereas the hardness measurements were sensitive to the annealing of dislocation-related defects in the recrystallization stage. It was concluded that positron annihilation techniques could be used as a precise tool for the quantitative estimation of the number of defects which were introduced by small deformations.

H.I.Kwon, I.S.Kim: Scripta Metallurgica et Materialia, 1995, 32[4], 607-10