Abstract: In this paper, the effect of RRA treatment on the microstructure evolution of a high strength aluminum alloy was investigated using DSC, TEM and SADP technology. The results show that the precipitation resulting from RRA is extremely fine and distributed homogeneously in the grains, being slightly coarser and more stable than that of T6 temper. While, the grain-boundary precipitation is very close to that of the alloy at T73 temper, being coarse and discontinuous. High retrogression temperature and long retrogression time leads to a more stable microstructure after re-aging.

Key words: DSC, TEM, RRA