RADIATION-DAMAGE IN ELECTRON-IRRADIATED AL-LI ALLOYS

Positron-lifetime measurements have been performed in electron-irradiated Al-Li alloys having 0.2 and 1.7 at. % Li content (solid solution) and 9.9 at. % Li (delta' phase precipitation). Theoretical calculations have been carried out in order to extract the annihilation characteristics in some defects expected in irradiated Al-Li alloys, such as vacancy-Li complexes and Li clusters. The theoretical results have been used to interpret the experimental measurements, attributing the measured lifetime in the as-irradiated alloys, tau=225 ps, to mainly vacancy-Li complexes. From the experimental results it is inferred that the Li content plays an important role in the annealing behavior of the alloys.