Research On The Structure-Activity Relationship Of Fe-Cr Alloy In Marine Environment Based On Synchrotron Radiation: Effect Of Cr Content

A solid-liquid interface will form on the surface of metal materials when immersed in the marine, which de -termines the corrosion resistance. Alloying is one of the most effective approaches to protect materials from corrosion failure by tuning the structure-activity relationship of the solid-liquid interface. Chromium is the decisive element in determining the corrosion resistance of iron-based alloys because it can increase electrode potential and promote passivation. However, up to date, the effect of chromium on materials service safety has not been adequately validated, which restricted the precise design and application of the corrosion resistance alloys. Herein, we probed the effect of Cr on structure-activity relationship with multiple characterization means including electrochemistry, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), surface enhanced Raman spectroscopy (SERS), synchrotron radiation grazing-incidence X-ray diffraction (GIXRD), and X-ray absorption fine structure (XAFS). The solid-liquid interface is mostly amorphous, with some nanocrystals. The addition of Cr can promote the increase of FeOOH and formation of FeCr2O4, with first increase and then decrease of Cr2O3. The enrichment of FeOOH and Cr2O3 improves corrosion resistance when Cr content is less than 30 wt.%. The formation of FeCr2O4 leads to the transformation from corrosion products to passive film when Cr content exceeds 18 wt.%. In addition, the lack of Cr2O3 and the formation of FeCr2O4 result in the descend of corrosion resistance at 40 wt.% Cr content.