Effect of Molybdenum on the Corrosion Behavior of High‐Entropy Alloys CoCrFeNi₂ and CoCrFeNi₂Mo_0.25 under Sodium Chloride Aqueous Conditions

Abstract

The corrosion behavior of high-entropy alloys (HEAs) CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl) at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276) and stainless steel 316L (UNS 31600) to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV) can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS) elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM) analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

The corrosion behaviour of CoCrFeNi-x (x = Cu, Al, Sn) high entropy alloy systems in chloride solution

“…In current usage, HEAs are multicomponent alloys with generally few solid solution phases of simple structure (such as body-centered cubic (BCC), face-centered cubic (FCC), or hexagonal close packed (HCP)) [14][15][16][17]. HEAs have been reported to have unusual properties of many types (including corrosion, mechanical, thermal and electrical properties, and wear properties [15][16][17][18][19][20][21][22][23]), and these behaviours suggest the potential for use in numerous applications, including nuclear, aerospace, energy, chemical, electronics, and marine infrastructure [15,17,24,25]. In particular, several HEA systems have been reported to show improved corrosion properties.…”

Effect of Pre-passivation on the Corrosion Behavior of PH13-8Mo Stainless Steel in Industrial—Marine Atmospheric Environment

“…In addition, a relatively low intensity Mo 3d spectra was recorded because of the oxidation states of the Mo 3d region overlap, the curve fitting becomes complicated to achieve the spectra owing to the almost similar energy levels of Mo 3d 3/2 and Mo 3d 5/2 . The signal intensity of Mo 4+ (228.40 eV, 231.40 eV) increased, which indicated that the prepassivation enhanced the enrichment of Mo and further made the passive film much denser (Kraack et al, 1995;Rodriguez et al, 2018). The addition of Mo into stainless steel has a significant effect on promoting the enrichment of Cr in the passive film and thus prolonged the induction period in Cl − concentrated environment (Sugimoto and Sawada, 1977;Li et al, 2017).…”

Microstructure, mechanical, and corrosion resistance properties of Al0.8CrFeCoNiCux high-entropy alloy coatings on aluminum by laser cladding

“…I corr is determined in the linear part of the polarization curve by deducting Tafel extrapolation, where the polarization resistance (R p ) is calculated according to formula (6). Therefore, I corr is the most important index for evaluating the corrosion resistance of WE [34][35][36]. According to table 6, as x increases I corr gradually increases, indicating that Cu reduces the corrosion resistance of Al 0.8 CrFeCoNiCu x HEAs.…”