Localized Corrosion Behavior of Non-Equiatomic NiFeCrMnCo Multi-Principal Element Alloys

• Published in: Electrochimica acta 2020-07, Vol.354
• Main Authors: Sahu, Sarita, Swanson, Orion J., Li, Tianshu, Gerard, Angela Y., Scully, John R., Frankel, Gerald S.
• Format: Article
• Language: English
• Subjects: Crystallographic pit morphology; MATERIALS SCIENCE; Multi-principal element alloys; Pitting corrosion
• ISSN: 0013-4686; 1873-3859

A series of single phase Ni38Fe20CrxMn21–0.5xCo21–0.5x multi-principal element alloys (MPEAs) were fabricated and their localized corrosion behavior was tested in 0.6 M NaCl solution. These MPEAs were found to be susceptible to localized corrosion, exhibiting pitting at room temperature, as indicated by positive hysteresis loops and low repassivation potentials observed in cyclic potentiodynamic polarization experiments. The pitting resistance increased with increasing Cr content. Interestingly, even the MPEAs with low chromium content, Ni38Fe20Cr6Mn18Co18 and Ni38Fe20Cr10Mn16Co16, exhibited passivity and localized corrosion. Here, the passivity observed in these low chromium MPEAs is likely derived from their relatively high nickel content. Crystallographic pit morphology was observed in most of these MPEAs, suggesting the absence of a salt film on the dissolving pit surface. Such crystallographic pit morphology indicates that the pit growth in most of these MPEAs was under charge-transfer/ohmic control.