The native oxide film on a model aluminium-copper alloy studied by XPS and ToF-SIMS

Surface analytical techniques were used to characterize the chemical composition and the thickness of the surface oxide on an AlCu2.2 %at alloy sample. ToF-SIMS analyses show that the oxide layer is thinner on the intermetallic particles (IMPs) as compared to the Al matrix. Combined with XPS, analyses reveal that IMPs are covered by aluminium and copper(I) oxide whereas the Al matrix is covered by aluminium oxide. Moreover, metallic copper segregates at the oxide/metal interface on both matrix and IMPs. The heterogeneities at the metal/oxide interfaces suggest that complex galvanic effects could occur between IMP and matrix substrate, and within the IMPs.