Microstructure and corrosion behaviour of ferritic steel-Zr-based metal waste form alloys in simulated ground water

摘要

The microstructure and corrosion behaviour of the metal waste form (MWF) alloys based on ferritic steel with Zr content in the range of 3-15 wt-% were investigated. The MWF alloys are composed of alpha-Fe and Fe-Zr phases and with the increase of Zr content, alpha-Fe phase gradually decreases and the relative content of Fe-Zr intermetallic phase also increases. TEM and XRD confirmed the presence of Fe2Zr and Fe23Zr6 intermetallics. Potentiodynamic polarisation curves showed The MWF alloys exhibited passivation behaviour in the simulated Kalpakkam (KGW) and Rajasthan ground water (RGW) media. Electrochemical impedance spectra revealed improved passive film stability in RGW than in KGW which is related to the formation of more stable adherent insoluble passive film in RGW. Higher Zr containing MWF alloy exhibited higher corrosion resistance than lower Zr containing MWF alloys. The relative content of Fe-Zr intermetallics is attributed for the corrosion resistance of The MWF alloys.