Microbially induced corrosion of D9 stainless steel–zirconium metal waste form alloy under simulated geological repository environment

Highlights: ► Metal waste form (MWF) alloys are susceptible to microbial growth. ► Microbes exhibited higher affinity towards the Zr rich intermetallic phases. ► Microbes formed crevices on the MWF surface and exhibited active corrosion dissolution. - Abstract: Metal waste form (MWF) alloy specimens were exposed to Bacillus sp. and Pseudomonas sp. cultured in simulated Kalpakkam and Rajasthan ground water media to study the microbially induced corrosion. Total viable count and epifluorescence microscopic results showed good bacterial attachment on MWF surface. Scanning electron microscopy and atomic force microscopy studies on etched MWF surfaces showed preferential bacterial adhesion on the Zr-rich intermetallic phases. Potentiodynamic polarization experiments showed active corrosion potential and higher current density for biofilmed surface. Electrochemical impedance spectroscopic study showed passive film weakening under the biofilm. Corrosion effect of Pseudomonas sp. is comparatively more than Bacillus sp.