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In the present work, laser shock peening was applied to the ultra-high strength Al-Zn-Mg-Cu alloys prepared by ingot metallurgy and spray forming. The microstructural evolution, pitting corrosion, intergranular corrosion resistance and electrochemical analysis were systematically investigated. The depth and number of corrosion pits caused by Al matrix, Al 7 Cu 2 Fe and Al 2 CuMg particles can be successfully reduced by laser shock peening. The depth of intergranular corrosion and the width of intergranular cracks also decreased. Cyclic polarization and electrochemical impedance spectroscopy tests also indicated the improved corrosion resistance caused by laser shock peening. The relationship between microstructural evolution and corrosion resistance was studied. • Corrosion resistance of ultra-high strength Al-Zn-Mg-Cu alloys is promoted by laser shock peening. • Al 2 CuMg and Al 7 Cu 2 Fe phases act as preferred sites for pitting corrosion. • Al 2 CuMg phase can cause deeper corrosion pits than Al 7 Cu 2 Fe phase. • Depth of pitting and intergranular corrosion are ameliorated by laser shock peening. • Residual compressive stress, line and surface defects is conducive to corrosion resistance. [ABSTRACT FROM AUTHOR]

The effects of trace Sc and Y on the corrosion behaviors of cold-drawn Al-0.2Ce alloys were revealed by scanning Kelvin probe force microscopy (SKPFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Electron Probe Micro-analyzer (EPMA), and electrochemical measurements. The results showed that the Al 3 Sc particles not only enable the increase of subgrain boundaries in the modified alloy after cold drawing but also improve the morphology and size of the Al 13 Fe 3 Ce phase. SKPFM analysis showed that the enrichment of Y around the Al 13 Fe 3 Ce phase in the modified alloy can decrease its electrochemical inertness and thus reduce the micro-galvanic corrosion susceptibility of the alloy. The results of the electrochemical analysis showed that the individual and composite addition of Sc and Y can improve the corrosion resistance of the cold-drawn Al-0.2Ce alloy. The corrosion potential and current of Al-0.2Ce-0.2Sc alloy are −0.892 V and 0.91 μA·cm−2, while the corrosion potential and current of Al-0.2Ce-0.1Y alloy are −0.918 V and 1.08 μA·cm−2, respectively. It is obvious that Sc element improves the corrosion resistance of Al-0.2Ce alloy more effectively than Y element. The corrosion depth of Al-0.2Ce-0.2Sc-0.1Y alloy was the smallest tested by immersion under the same conditions, and its corrosion potential and corrosion current were −0.842 V and 0.79 μA·cm−2, respectively, corresponding to the best corrosion resistance. The formal mechanism of pitting corrosion in the alloys is also discussed. [Display omitted] • Effect of Sc on microstructure and corrosion of Al-0.2Ce alloy was revealed. • The enrichment of Y atoms around Al 13 Fe 3 Ce can reduce the potential difference. • The corrosion behaviors of pitting corrosion induced by Al 13 Fe 3 Ce was discussed. • The equivalent circuit of the studied alloys was identified. [ABSTRACT FROM AUTHOR]