Abstract
The influence of Li+ ions on the corrosion behaviour of the Al–Li alloy 8090–T851 and of commercially pure aluminium in aqueous solutions at pH 12 was studied by weight loss and electrochemical polarisation methods. The inhibiting role of Li+ was concentration dependent, corrosion rate decreasing linearly with log [Li+] in the concentration range 10-4-10-1 mol L-1. A change from general to pitting corrosion was evident from scanning electron microscopy studies. Polarisation studies revealed that Li+ primarily acts as an anodic inhibitor (passivator). Passive film formation and stability also become more feasible with increasing Li+ concentration. Pitting potential was dependent on the Cl- ion concentration in the solution. Both materials were affected similarly by the presence of Li+ ions, the corrosion rate of the alloy being slightly lower. This is attributed to the lithium in the alloy acting as a source of lithium for passive film formation.
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