Enhanced pitting corrosion resistance of CoCrFeMnNi high entropy alloy in the presence of Desulfovibrio vulgaris via nitrogen doping

Corrosion-resistant high nitrogen high entropy alloys (HEAs) were manufactured by pressurized metallurgy. This work revealed the inhibitory effect of nitrogen on pitting corrosion of HEAs caused by sulfate reducing bacterium Desulfovibrio vulgaris. Results indicated that HEA-0 N was susceptible to pitting corrosion and sulfidation under attack of D. vulgaris, whereas the addition of nitrogen significantly decreased the pitting sensitivity. Pitting potentials of HEA-0.52 N and HEA-1.23 N increased by 133% and 171%, respectively compared to HEA-0 N in the presence of SRB. X-ray photoelectron spectroscopy results unveiled that nitrogen enriched in passive film and strengthened it by increasing fraction of Cr2O3 and Fe3+ox. Surface of the nitrogen-alloyed HEAs exhibited less defective passive films as revealed by Mott-Schottky results. Nitrogen doping provides a novel insight into the design of microbial corrosion resistant HEA.