A positron annihilation study of vacancy recovery in quenched single crystals of Al-1·2 × 10−2at.% In

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Abstract
Doppler-broadening measurements of positron annihilation in single crystals of Al-1·2 × 10−2 at.% In have been made in terms of the customary peak, S, and wing, W, lineshape parameters. Results have been obtained for samples in both well-annealed and quenched (from 753 K) states, as well as for quenched samples as a function of isochronal annealing. In the as-quenched state, S and W are increased and decreased, respectively, by 4% and 16%, with respect to the corresponding annealed state values. The bulk of recovery of both S and W occurs in a nearly linear (with temperature) interval between about 300 and 400 K, by which tempera ture (400 K) W exhibits strong super-recovery. The W parameter returns, ìn a complex fashion, towards its annealed state value over the range 400–500 K; in this same interval, S rises from close to its annealed state value to a peak at 450 K before falling again towards its reference value. The recovery features observed here are in marked contrast to results from parallel studies on other dilute Al alloys, and show a strong influence of In on the vacancy recovery characteristics of Al.