Dynamic Polarization Behaviors of Equimolar CoCrFeNi High-Entropy Alloy Compared with 304 Stainless Steel in 0.5 M H2SO4 Aerated Aqueous Solution

Three corrosion potentials and three corrosion current densities are clearly identified before the passivation for both dynamic polarization curves of equimolar CoCrFeNi high-entropy alloy (HEA) and 304 stainless steel (304SS) in 0.5 M H2SO4 aerated aqueous solution, by decomposing anodic and cathod...

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Published in:Materials 2022-10, Vol.15 (19), p.6976
Main Authors: Yen, Chao-Chun, Tsai, Ting-Lun, Wu, Bo-Wei, Lo, Yu-Chieh, Tsai, Ming-Hung, Yen, Shiow-Kang
Format: Article
Language:English
Subjects:
Aeration
Alloys
Anodic polarization
Aqueous solutions
Austenitic stainless steels
Bond energy
Cathodic polarization
Corrosion currents
Corrosion potential
Corrosion resistance
Current density
Density functional theory
Electrodes
Energy
First principles
High entropy alloys
Intermetallic compounds
Manganese
Mass spectrometry
Metals
Oxide coatings
Scientific imaging
Stainless steel
Sulfuric acid
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Summary:Three corrosion potentials and three corrosion current densities are clearly identified before the passivation for both dynamic polarization curves of equimolar CoCrFeNi high-entropy alloy (HEA) and 304 stainless steel (304SS) in 0.5 M H2SO4 aerated aqueous solution, by decomposing anodic and cathodic polarization curves. The passivated current density of the former is greater than the latter, compliant with not only the constant of solubility product (ksp) and redox equilibrium potential (Eeq) of each metal hydroxide but also the sequence of bond energy (Eb) for monolayer hydroxide on their facets derived from the first principle founded on density function theory. However, the total amount of ion releasing from HEA is less than 304SS, since the hydroxide/oxide film formed in the air of the latter containing greater amounts of Fe(Ⅱ) and Mn(Ⅱ) is less stable around corrosion potentials while they are further oxidized into more stable Fe(Ⅲ) and Mn(ⅢorⅣ) with much lower ksp, leading to the much less increasing ratios of ion releases from 0.25 to 0.6 V.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15196976