The alloy was heat-treated in order to obtain samples which contained vacancy-Li clusters, and samples which contained both clusters and dislocation loops. Positron lifetime parameters were measured, in both cases, as a function of temperatures ranging from 10 to 295K. In the case of samples which contained only vacancy-Li complexes, 2 lifetimes were observed over the entire temperature range. The average lifetime, the long component, and its associated intensity remained roughly constant from 100 to 295K, and decreased between 100 and 10K. In samples which contained 2 types of positron trap, 2 lifetimes were observed only at temperatures ranging from 100 to 295K; where the presence of loops led to a sharp decrease in the long lifetime, and an increase in its associated intensity. Within the temperature range of 10 to 100K, the only detectable lifetime decreased; as observed in the case of samples which contained vacancy-Li complexes. The results were explained in terms of a strong temperature dependence of the rate of trapping in loops, and a reversible pinning effect of Li atoms on open-volume defects.

Temperature Dependence of Positron Trapping at Defects in an Al-Li Alloy J.Del Río, N.De Diego, F.Plazaola: Journal of Physics - Condensed Matter, 1998, 10[24], 5327-33