Corrosion behavior of NiCrFe Alloy 600 in high temperature, hydrogenated water

摘要: Abstract The corrosion behavior of Alloy 600 (UNS N06600) is investigated in hydrogenated water at 260 °C. kinetics are observed to be parabolic, the parabolic rate constant being determined by chemical descaling 0.055 mg dm −2  h −1/2 . A combination scanning and transmission electron microscopy, supplemented energy dispersive X-ray spectroscopy grazing incidence diffraction, used identify oxide phases present (i.e., spinel) characterize their morphology thickness. Two layers identified: an outer, ferrite-rich layer inner, chromite-rich layer. photoelectron with argon ion milling target factor analysis applied determine spinel stoichiometry; inner (Ni 0.7 Fe 0.3 )(Fe Cr ) 2 O 4 , while outer 0.9 0.1 0.85 0.15 distribution trivalent iron chromium cations essentially same as that found previously stainless steel oxides, thus confirming invariant nature solvi immiscible binary 3 –FeCr (or NiFe –NiCr ). Although oxidation occurred non-selectively, excess quantities nickel(II) were not found. Instead, nickel was accounted for recrystallized metal layer, additional ferrite formed pickup ions from aqueous phase, selective release phase.