A review on Corrosion of High Entropy Alloys: Exploring the Interplay Between Corrosion Properties, Alloy Composition, Passive Film Stability and Materials Selection

AbstractMolecular dynamics is applied to explore the deformation mechanism and crystal structure development of the AlCoCrFeNi high-entropy alloys under nanoimprinting. The influences of crystal structure, alloy composition, grain size, and twin boundary distance on the mechanical properties are carefully analyzed. The imprinting load indicates that the highest loading force is in ascending order with polycrystalline, nano-twinned (NT) polycrystalline, and monocrystalline. The change in alloy composition suggests that the imprinting force increases as the Al content in the alloy increases. The reverse Hall–Petch relation found for the polycrystalline structure, while the Hall–Petch and reverse Hall–Petch relations are discovered in the NT-polycrystalline, which is due to the interactions between the dislocations and grain/twin boundaries (GBs/TBs). The deformation behavior shows that shear strain and local stress are concentrated not only around the punch but also on GBs and adjacent to GBs. The slide and twist of the GBs play a major in controlling the deformation mechanism of polycrystalline structure. The twin boundary migrations are detected during the nanoimprinting of the NT-polycrystalline. Furthermore, the elastic recovery of material is insensitive to changes in alloy composition and grain size, and the formability of the pattern is higher with a decrease in TB distance.

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Novel (CoFe2NiV0.5Mo0.2)100−xNbx Eutectic High-Entropy Alloys with Excellent Combination of Mechanical and Corrosion Properties

Acta Metallurgica Sinica (English Letters) ◽

10.1007/s40195-020-01072-6 ◽

2020 ◽

Vol 33 (8) ◽

pp. 1046-1056

Author(s):

Ren Li ◽

Jing Ren ◽

Guo-Jia Zhang ◽

Jun-Yang He ◽

Yi-Ping Lu ◽

...

Keyword(s):

High Entropy Alloys ◽

Corrosion Properties ◽

High Entropy ◽

Mechanical And Corrosion Properties

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Comparative EIS Study of AlxCoCrFeNi Alloys in Ringer’s Solution for Medical Instruments

Metals ◽

10.3390/met11060928 ◽

2021 ◽

Vol 11 (6) ◽

pp. 928

Author(s):

Pedro P. Socorro-Perdomo ◽

Néstor R. Florido-Suárez ◽

Ionelia Voiculescu ◽

Julia C. Mirza-Rosca

Keyword(s):

Corrosion Resistance ◽

Passive Film ◽

Time Constant ◽

Equivalent Circuits ◽

High Entropy Alloys ◽

Impedance Spectra ◽

High Entropy ◽

Al Content ◽

Medical Instruments ◽

Very High

Depending on the properties required for the medical instruments, compared with the classical materials, the high-entropy alloys (HEAs) are a versatile option. Electrochemical Impedance Spectroscopy (EIS) measurements have been performed on AlxCoCrFeNi-type high-entropy alloys with various concentrations of Al content (x = 0.6, 0.8, and 1.0) in order to characterize their passive film and corrosion resistance at 37 °C under infectious simulated physiological conditions (Ringer´s solution acidulated with HCl) at pH = 3. The impedance spectra were obtained at different potential values between −0.7 and +0.7 V vs. SCE. Analysis of the impedance spectra was carried out by fitting different equivalent circuits to the experimental data. Two equivalent circuits, with one time constant and two time constants respectively, can be satisfactorily used for fitting the spectra: one time constant represents the characteristics of the compact passive film, and the second one is for the porous passive film. With the decreasing of Al content, the obtained EIS results are correlated with the evolution of the microhardness and microstructure, which is characterized by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-Ray Spectroscopy (EDAX). It can be observed for all alloys that the resistance of the passive film is very high and decreases with the potential: the very high resistance of the passive film implies a high corrosion resistance, which can be assigned to the formation of the protective oxide layer and demonstrates that the analyzed alloys fulfill the prerequisites for their use as new materials for the manufacturing of medical instruments.

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