Recovery of deformed iron studied by positrons

The isochronal annealing of two plastically deformed irons of 99.998% and 99.86% purities is studied by positron lifetime and annihilation line shape measurements. The results show that trapping of positrons is caused by dislocations. At around 300° C a recovery process attributed to a rearrangement of dislocation structure is observed in the pure but not in the impure iron. The positron lifetime in deformed and recrystallized state is found to be 167 ps and 117 ps, respectively.