Microstructural Evolution of a New Aerospace 7XXX Alloy during Retrogression and Re-Ageing Treatment
RRA treatment was applied to a high-Zn, 7XXX alloy under development for aerospace applications. Microstructure of the alloy is studied at different stages of the 3-step ageing process, by Transmission Electron Microscopy, in order to understand the corresponding evolution of mechanical and corrosion properties. The Compression Yield Strength at the end of the high temperature step was found higher than at the end of the 1st step, contrary to the conventional RRA treatment. After re-ageing, the final CYS turned out significantly higher than at the T6 temper of the alloy, while the material remained sensitive to exfoliation corrosion.
W.J. Poole, M.A. Wells and D.J. Lloyd
M. Tanaka et al., "Microstructural Evolution of a New Aerospace 7XXX Alloy during Retrogression and Re-Ageing Treatment", Materials Science Forum, Vols. 519-521, pp. 345-350, 2006