Localized corrosion of Al-Li alloys

Most aluminium alloys have good corrosion resistance in natural atmospheres. Heat treatable alloys can however be susceptible to grain boundary attack in certain tempers as a result of local electro-chemical cells caused by precipitates and precipitate free zones. Al-Li binary alloys have been reported to be susceptible to intergranular corrosion resulting from the anodic nature of the Al-Li precipitates. The addition of magnesium, alters the transformation sequence and Al-Li-Mg alloys have been reported to have good resistance to intergranular corrosion. The experimental work described in this paper utilized accelerated corrosion tests established to predict long-term outdoor behaviour of existing alloy systems. The test results for lithium-containing alloys ought to be correlated in a similar manner, but there is a lack of documented data on the corrosion of these alloys in natural environments. The results reported here should be treated with caution when comparing with known alloy systems.