Positron annihilation lifetime measurements were performed on Fe, Fe-Cu and Fe-Si samples which had been irradiated with electrons at 77K, and on Ni which had been deformed at room temperature. Isochronal annealing results indicated that vacancies became mobile at temperatures above 200K, and formed micro-voids in Fe. However, in Fe-Cu and Fe-Si alloys, the interaction between vacancies and solute atoms markedly suppressed micro-void formation. In Fe-Cu, vacancy-Cu complexes rather than micro-void formation appeared to form. In deformed Ni, the positron lifetime decreased gradually as the isochronal annealing temperature was increased. It was suggested that, in deformed Ni, positrons were trapped and annihilated at complexes which involved dislocations and deformation-induced vacancies.

E.Kuramoto, H.Abe, M.Takenaka, F.Hori, Y.Kamimura, M.Kimura, K.Ueno: Journal of Nuclear Materials, 1996, 239, 54-60