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MM: Fachverband Metall- und Materialphysik

MM 53: Structural Materials (Steels, light-weight materials, high-temperature materials) - II

MM 53.5: Vortrag

Donnerstag, 19. März 2020, 12:45–13:00, BAR 205

Oxide Breakdown and Anodic Corrosion of Nickel Base Alloys — •Dominik Dworschak, Hsiu-Wei Cheng, and Markus Valtiner — TU Wien, Applied Physics, Vienna, AT

Transpassive and pitting corrosion behaviour of advanced materials such as nickel base alloys (NBAs) determines corrosion resistance in extreme environments. While Cr and Mo enhanced passivity is well characterized, mechanism of transpassive dissolution as well as pitting and subsequent repassivation, e.g. occurring during active corrosion or pickling, are unclear. Here, elemental dissolution currents during high anodic polarization and repassivation of a series of nickel base alloys were quantified using an ICP-MS flow cell. At high anodic potentials non-stoichiometric and decelerated dissolution rates depend on the selective segregation/dissolution of alloying elements and transpassive passive film formation. Oxide breakdown depends on the solution chemistry and local pH that establishes during dissolution. Samples after corrosion experiment were examined by X-ray photoelectron spectroscopy and high spatial resolution synchrotron X-ray fluorescence to revealing local nickel depletion, while chromium and iron were enriched in corroded areas. We also discuss the influence of ICP-MS cell design on the corrosion mechanism and hence on obtained results.