is probably a consequence of the combination of the influence
of the fluorine containing environment and the field assisted flow of
the prior formed barrier oxide layer. The energy dispersive X-ray spectroscopy
(EDS) spectrum of a spot in the anodic oxide layer displaying
the elements present in the film is shown in Fig. 1c. The EDS spectrum
indicates the presence of fluorine in the Barker's reagent-formed oxide
layer, which confirms the ingress of fluoride ions through the film
fromthe electrolyte. In Fig. 1d, an opticalmicrograph showing differentcolour contrasts with respect to the individual grains of the alloy, when
the Barker's reagent-anodized AA5083-O surface is viewed under polarized
light, is displayed. The distinctive colour contrasts show that the
grain-distinct ridge-like features produce different orientation dependent
interference