AbstractStructure change during the reversion process in an Al−12at.%Li alloy above the metastable δ′ solvus was investigated using a time-resolved small-angle x-ray scattering technique with synchrotron radiation. Results showed that the reversion process started after a short incubation time and that the growth of the stable δ phase began before completion of the δ′ dissolution. The radius of gyration of the second phase particles showed little change in the initial stage of reversion, then increased with time, suggesting the presence of diffuse interfaces between the dissolving δ′ particles and the matrix. It is suggested that the undissolved δ′ particles serve as the nuclei of the more stable δ precipitates, which continue to grow with their radii of gyration showing a parabolic power law in the early stage of growth followed by the familiar coarsening kinetics.
A synchrotron radiation camera and data acquisition system for time-resolved X-ray scattering studies
