Corrosion behavior of FeCrAl alloy and NiCr coated Zircaloy-4 in hydrogenated water

Corrosion behavior of FeCrAl alloy and Zircaloy-4 coated with NiCr in hydrogenated water was studied. FeCrAl alloy exhibited non-uniform corrosion and increased surface roughness. Its inner oxides were mainly Fe/Cr oxides, while the outer oxides were mostly Fe spinels. NiCr coating was well-covered on the Zircaloy-4 substrate after exposure. Ni-rich spinels, Ni/Zr oxides, Fe oxides and Cr oxides were formed on the surface. Crack initiation and high porosity induced evident internal oxidation at the coating-substrate interface with the appearance of transition regions, where Ni-, Zr-, Cr- and Al-containing oxides occupied the dominance and their growth stress increased the risk of coating exfoliation.