External oxidation of aluminium-lithium alloys

Abstract The thermal oxidation dynamics of cold rolled aluminium-3%lithium foils was studied as a function of the annealing temperature, time and environmental gas pressure, by means of Rutherford backscattering spectrometry, thermal neutron depth profiling and scanning electron microscopy. Highly complex behaviour was found, which includes the depletion of lithium atoms from sub-surface layers and their enrichment in the surface area as oxide. The ratio of lithium to oxygen is usually far from stoichiometric. The surface transformation into oxide proceeds very rapidly in the first few minutes, and subsequently hardly shows any change.