Positron annihilation spectroscopy was used to study the formation and annealing of vacancy clusters in 16Cr15Ni3Mo austenitic steels and Fe–36%Ni model alloys and in the same compounds containing 1.02 and 2.5wt%Ti respectively. Defects were induced by electron (5MeV) irradiation at 270 to 573K. How a developed initial dislocation structure influenced the accumulation and annealing of vacancy defects in these steels and alloys was analyzed. It was shown that vacancies interacted with Ti atoms. As a result, the Ti-containing steels and alloys exposed to radiation at 270 to 423K had an enhanced concentration of fine vacancy clusters decorated with Ti, which were thermally stable up to 450K. A high initial dislocation density in the deformed steels and alloys led to a several-fold decrease in the concentration of vacancy clusters as compared to their concentration in the solution annealed state. The formation of fine TiC particles in Ti-modified deformed steel was monitored at the annealing temperatures of 850 to 1070K.

Positron Annihilation Study of Effects of Ti and Plastic Deformation on Defect Accumulation and Annealing in Electron-Irradiated Austenitic Steels and Alloys. A.P.Druzhkov, V.L.Arbuzov, D.A.Perminov: Journal of Nuclear Materials, 2005, 341[2-3], 153-63