Depth Distribution of Lithium in Oxidized Binary Al-Li Alloys Determined by Secondary Ion Mass Spectrometry and Neutron Depth Profiling

Oxidation of binary Al-Li alloys during short exposures at 530° C and long exposures at 200°C was studied with regard to the Li distribution. Secondary ion mass spectrometry (SIMS) and neutron depth profiling (NDP) were used to obtain quantitative Li depth profiles across the surface oxide layer and the underlying alloy. The underlying alloy was depleted in Li as a result of oxidation at 530 and 200° C. The SIMS and NDP results showed good mutual agreement and were used to evaluate the oxide thickness, the Li concentration at the oxide-alloy interface, and the mass balance between oxide and alloy. The Li depletion profiles in the alloy were also calculated using the interdiffusion coefficients reported in the literature and compared with the measured profiles; the two profiles differed at 530°C but showed good agreement at 200° C.