The vacancy defect evolution under electron irradiation in austenitic Fe–34.2wt%Ni alloys containing oversized (Al) and undersized (Si) alloying elements was investigated by positron annihilation spectroscopy at 300 to 573K. It was found that the accumulation of vacancy defects was considerably suppressed in the silicon-doped alloy. This effect was observed at all the irradiation temperatures. The obtained results provided evidence that the silicon-doped alloy forms stable low-mobility clusters involving several Si and interstitial atoms, which were centers of the enhanced recombination of migrating vacancies. The clusters of Si-interstitial atoms also modify the annealing of vacancy defects in the Fe–Ni–Si alloy. The interaction between small vacancy agglomerates and solute Al atoms was observed in the Fe–Ni–Al alloy under irradiation at 300 to 423K.

The Effect of Alloying Elements on the Vacancy Defect Evolution in Electron-Irradiated Austenitic Fe–Ni Alloys Studied by Positron Annihilation. A.P.Druzhkov, D.A.Perminov, A.E.Davletshin: Journal of Nuclear Materials, 2009, 384[1], 56-60