Microstructural analysis of oxidised Al-base coated EUROFER97 for corrosion protection
EUROFER97 specimens Al-base coated using different processes, either chemical vapour deposition or electroplating, were oxidised at 980 °C for 60 minutes and 760 °C for 90 minutes to understand whether this 2-step oxidation process could provide a suitable oxide layer able to offer both corrosion protection and a tritium permeation barrier. The near surface region of the specimens was characterised revealing that the 2-step oxidation process induced the formation of a ≈0.6 µm α-Al2O3 layer on an intermetallic interdiffusion microstructure of ≈80 µm depth, highly decorated with Al-rich second phases and voids. Although the electroplated specimen appeared to present the most suitable microstructure, the current 2-step oxidation process produced a high density of voids, so further optimisations are still needed.