Study of recovery in plastically deformed Al-Li-based alloy by positron annihilation

Positron annihilation mean lifetime measurements have been performed on two samples of the commercial alloy [(8090) Al-Li-Cu-Mg-(Zr)]. One sample was deformed (37.5%) at room temperature and subjected to isochronal annealing. The temperature was varied from 300K to 623K. The other one was homogenized at 823 K and subjected to isothermal annealing at 873 K. The time of annealing varied from 0 to 12 h in steps of 2 h. Evidence of nonspurious lifetime component, in both cases, have been observed. The results of the plastically deformed samples (<(tau)over bar> = 202 +/- 2 ps) are interpreted as trapping of positrons in dislocations and Li-rich zones. On the other hand the results of the homogenized sample (<(tau)over bar> = 183 +/- 2 ps) are interpreted as trapping of positrons in Li-rich zones only.