Corrosion Behavior of Aluminum-Lithium Alloys

Corrosion behavior of three aluminum-lithium (Al-Li) alloys was investigated in aerated 0.5 M sodium sulfate (Na2SO4), deaerated 3.5% sodium chloride (NaCI), and aerated 3.5% NaCI. Corrosion behavior of the Aluminum Association (AA) alloys 2090-T8E41 (UNS A92090, sheet), AA 8090-T851 (UNS A98090, sheet), and AA 8090-T82551 (UNS A98090, bar) was compared to behavior of the conventional AA 7075-T6 (UNS A97075, sheet). Uniform corrosion was the predominant form of attack in aerated Na2SO4 and deaerated NaCI, although some localized attack resulted from corrosion of intermetallics on specimen surfaces. Pitting was the main form of attack in aerated NaCI. In all three media, the sheet materials corroded at a similar rate, but the bar form of AA 8090 corroded at a lower rate. Pretreatment of the alloys by immersion in a cerium (Ce) solution inhibited pitting in aerated NaCI but only for a short period.