Abstract: 7136-0.35La aluminum alloy was subjected to solid solution treatment in single-, double-, and three-stage respectively and then single-stage aging, and the solid-solution metallography, tensile fracture morphology and energy spectra, alloy hardness, fracture properties, and electrochemical parameters were tested by scanning electron microscope, hardness tester, universal tensile tester, electrochemical workstation and other equipment. The results show that the re-dissolution effect for three-stage treated solid solution microstructure is better, and the number of corrosion cracking sources is preliminarily reduced. The elongation of the three-stage solution treated then aged alloy is 13.65%, which is 21.9% higher than that single-stage treated, and with ductile fracture as the primary fracture mode. However, the three aged alloys solid-solution treated in single-, double- and three-stages show similar resistance to electrochemical corrosion, so the single stage solution treatment is preferred when taking the corrosion property as the main criteria.

Key words: multi-stage solid solution, solid-solution state structure, crack source, electrochemical corrosion resistance