The effect of minor Zn alloying on corrosion resistance of Al-Li alloys (2090 and 2091) was investigated. By addition of 0.7% Zn, the SCC resistance as well as exfoliation corrosion resistance of 2090 and 2091 alloys are improved remarkably. The addition of Zn facilitates pitting corrosion and enhances general corrosion so that it suppresses selective attack in the area along the grain or subgrain boundary. This observation indicates localized corrosion on the grain or subgrain boundary is

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... ly related to the susceptibility to SCC. Massive or film-shaped compounds with a high concentration of Zn are found on the grain boundaries in the peak-aged Zn added 2091 alloy. The precipitation of these compounds is likely to result in relieving the difference in electrochemical potential between the grain boundaries and grain bodies.