Effect of chromium on the electrochemical properties of iron aluminide intermetallics

Zamanzade, Mohammad; Barnoush, Afrooz

doi:10.1016/j.corsci.2013.10.002

Cited by 28 publications

(14 citation statements)

References 48 publications

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“…EDX spectrum 4 in Figure 7 reveals the presence of small quantities of Co in the surface film of the (Al) phase. As mentioned in the Introduction, the incorporation of transition metals (TM) in the surface film of aluminum enhances the protectiveness of the film in crystalline Al-TM alloys [30][31][32][33] and Al-Cr-Fe CMAs [34,35]. Detection of Cl´in the EDX spectra of Al (spectrum 4) and Al 9 Co 2 (spectrum 5) provides evidence of interaction of Cl´on the surface film of a metal, consistent with previous works [63,64].…”

Section: Comparison Of the Polarization Behavior Of The Various Composupporting

confidence: 70%

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

Lekatou

Sfikas

Petsa

et al. 2016

Metals

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Hypereutectic Al-Co alloys of various Co contents (7-20 weight % (wt.%) Co) were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co) to coarse primary Al 9 Co 2 predominance (20 wt.% Co). Co dissolution in Al far exceeded the negligible equilibrium solubility of Co in Al; however, it was hardly uniform. By increasing the cobalt content, the fraction and coarseness of Al 9 Co 2 , the content of Co dissolved in the Al matrix, and the hardness and porosity of the alloy increased. All alloys exhibited similar corrosion behavior in 3.5 wt.% NaCl with high resistance to localized corrosion. Al-7 wt.% Co showed slightly superior corrosion resistance than the other compositions in terms of relatively low corrosion rate, relatively low passivation current density and scarcity of stress corrosion cracking indications. All Al-Co compositions demonstrated substantially higher resistance to localized corrosion than commercially pure Al produced by casting, cold rolling and arc melting. A corrosion mechanism was formulated. Surface films were identified.

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Section: Comparison Of the Polarization Behavior Of The Various Composupporting

confidence: 70%

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

Lekatou

Sfikas

Petsa

et al. 2016

Metals

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show abstract

“…In the sample with a higher concentration of chromium, some part of the iron oxide in the passive layer was replaced by Cr 3+ Contribution of Cr ions (Cr 3+ and Cr 6+ ) to the increase of the effective capacitance and donor density of the passive layers was seen based on the electrochemical measurements. The effect of Cr on the polarization resistance was more obvious at high anodic potentials where the strong enrichment of the passive layer with Cr 3+ and Cr 6+ could make a more protective p-type passive layer, instead of the n-type (Al 3+ -rich) layer, for example at lower potentials or in alloys without Cr [101]. Additionally, it has been shown that the reduction of the flat-band potential after the addition of 5 at.…”

Section: Electrochemical Properties Of Fe-al Intermetallicsmentioning

confidence: 92%

“…Cr is one of the most important alloying elements and its input on various thermo-mechanical and electrochemical properties has already been studied extensively [23,25,[101][102][103][104]. Palm experimentally determined an isothermal section for the Fe-Al-Cr system at 1000˝C [82].…”

Section: Effect Of Cr On the Mechanical Properties Of Fe-al Intermetamentioning

confidence: 99%

“…The contributions of alloying elements on the electrochemical properties of iron aluminides in aqueous environments have rarely been studied. Electrochemical impedance spectroscopy (EIS) and the Mott-Schottky (MS) methods were performed to characterize the passive film of binary and ternary alloys with different Cr content in the near-neutral and Cl´-free solutions [101]. The existence of high donor densities in the passive layers [101] causes semi-conductive behavior.…”

Section: Electrochemical Properties Of Fe-al Intermetallicsmentioning

confidence: 99%

“…Electrochemical impedance spectroscopy (EIS) and the Mott-Schottky (MS) methods were performed to characterize the passive film of binary and ternary alloys with different Cr content in the near-neutral and Cl´-free solutions [101]. The existence of high donor densities in the passive layers [101] causes semi-conductive behavior. In the sample with a higher concentration of chromium, some part of the iron oxide in the passive layer was replaced by Cr 3+ Contribution of Cr ions (Cr 3+ and Cr 6+ ) to the increase of the effective capacitance and donor density of the passive layers was seen based on the electrochemical measurements.…”

Section: Electrochemical Properties Of Fe-al Intermetallicsmentioning

confidence: 99%

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A Review on the Properties of Iron Aluminide Intermetallics

2016

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Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore, iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications, such as brake disks for windmills and trucks, filtration systems in refineries and fossil power plants, transfer rolls for hot-rolled steel strips, and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i) alloy composition; (ii) microstructure; and (iii) number (type) of defects on the thermo-mechanical properties. Additionally, environmental degradation of the alloys, consisting of hydrogen embrittlement, anodic or cathodic dissolution, localized corrosion and oxidation resistance, in different environments should be well known. Recently, some progress in the development of new micro-and nano-mechanical testing methods in addition to the fabrication techniques of micro-and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements, environmental items and crystal structure on the deformation behavior of alloys. In this paper, we will review the extensive work which has been done during the last decades to address each of the points mentioned above.

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A new index to estimate the corrosion resistance of aluminium‐containing steel

Ooi

2024

Materials & Corrosion

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A new index that estimates the corrosion resistance of aluminium‐containing steel is established and verified. It is based on the well‐known pitting resistance equivalent number (PREN) but accounts for aluminium additions. It is shown that aluminium enhances the corrosion resistance of chromium‐containing steel, with a coefficient of 5.2. The new corrosion resistance index (CRI) is as follows CRI = Cr + 3.3Mo + 16N + 5.2Al. A minimum of 4 wt% of chromium addition is needed. In addition, the atomic ratio of chromium to aluminium addition needs to be higher than 1, for this new index to be valid. This new index allows for simple alloy design guidelines for steel applications that require improved corrosion resistance. Analysis of the data from the literature shows that this index becomes inaccurate when the corrosion environment is in the presence of NaCl, and aluminium becomes less effective in enhancing corrosion resistance.

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Effect of chromium on the electrochemical properties of iron aluminide intermetallics

Cited by 28 publications

References 48 publications

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

A Review on the Properties of Iron Aluminide Intermetallics

A new index to estimate the corrosion resistance of aluminium‐containing steel

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