Abstract
The formation and dissolution of δ′ precipitates has been followed by positron annihilation spectroscopy in two Al-Li alloys (Al–9·9 at.% Li and Al-8·6 at.% Li-0·04 at.% Zr). Lifetime measurements have been performed by annealing the samples from the as-quenched state to 750 K, which is well above the dissolution temperature for the δ′-phase Al3Li. The results suggest that small δ′-like regions are present in the as-quenched state, and that they dissolve at around 430 K, in agreement with previous results in the literature. The technique has proved to be very sensitive to the growth and dissolution of δ′ precipitates owing to the high positron affinity to Li in an Al matrix.