Defect annealing and the formation of Li-rich clusters in Al-Li alloys

Abstract

Positron annihilation lineshape measurements are conducted on pure Al, Al-1.9 at.% Li and Al-(12.0-12.5) at.% Li alloys. The recovery of each sample following quench and/or cold-work treatments is discussed in terms of vacancy migration and clustering, dislocation annealing and precipitation. The results indicate precipitation in both alloy concentrations but no positron trapping at dislocations. All cold-worked alloys show large vacancy clustering effects, providing strong evidence of vacancy agglomeration at precipitates.