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Al‐Badairy, H.; Tatlock, G. J.

doi:10.1023/a:1004590915746

Cited by 24 publications

(15 citation statements)

References 3 publications

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“…The third possible oxide growth mechanism is based on the formation of a duplex oxide layer and occurs when the diffusion rates of aluminium and oxygen are almost equal [2][3][4]. Several papers have been published concerning the diffusion and growth mechanisms of alumina layers on FeCrAl alloys at high temperatures [3,[5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics

Engkvist

Bexell

Grehk

et al. 2009

Materials & Corrosion

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The superior high temperature oxidation resistance of FeCrAl alloys relies on the formation of a dense and continuous protective aluminium oxide layer on the alloy surface when exposed to high temperatures. Consequently, the aluminium content, i.e. the aluminium concentration at the alloy-oxide layer interface, must exceed a critical level in order to form a protective alumina layer. In the present study the oxidation behaviour of six different FeCrAl alloys with Al concentrations in the range of 1.2-5.0 wt% have been characterised after oxidation at 900 8C for 72 h with respect to oxide layer surface morphology, thickness and composition using scanning electron microscopy, energy dispersive X-ray spectroscopy and Auger electron spectroscopy. The results show that a minimum of 3.2 wt% Al in the FeCrAl alloy is necessary for the formation of a continuous alumina layer. For Al concentrations in the range of 2.0-3.0 wt% a three-layered oxide layer is formed, i.e. an oxide layer consisting of an inner alumina-based layer, an intermediate chromia-based layer and an outer iron oxide-based layer. In contrast, the 1.2 wt% Al FeCrAl alloy is not able to form a protective oxide layer inhibiting extensive oxidation.

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Section: Introductionmentioning

confidence: 99%

High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics

Engkvist

Bexell

Grehk

et al. 2009

Materials & Corrosion

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“…Y segregation to the oxide-metal interface and to oxide grain boundaries is commonly observed [23,24]. The effect of Y could be to modify the diffusion mechanisms [19,25] and/or influence the stress relaxation during cooling [26]. New experimental results on the mechanisms of diffusion, scale growth and stress relaxation have been recently obtained [27,28].…”

Section: Discussionmentioning

confidence: 99%

“…1. Spalled area coinciding with an emergent grain boundary of the substrate (alloy M1 after 24 h at 1060 C) [19] specimens without Y (M1) and also the hydrogen purified M5 show small microvoids at the metal±oxide interface. YAM precipitates (Al 2 Y 4 O 9 ) were identified by electron diffraction in the metal at a short distance from the interface (1 to 4 mm).…”

Section: Scale Morphology and Spallationmentioning

confidence: 99%

High Temperature Oxidation of UHP-Based Fe20Cr5Al Alloys

Mennicke¹,

Schumann²,

Al‐Badairy

et al. 1998

phys. stat. sol. (a)

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UHP-base alloys have been used to study the effects of sulfur and yttrium on the oxidation resistance of ferritic Fe20Cr5Al alloys. Doping with sulfur and/or yttrium gave a series of alloys with sulfur contents between 0.2 to 50 ppm sulfur, with or without yttrium (0.1 wt% maximum). The a-alumina scale and the metal±oxide interface structures were investigated after oxidation between 1060 and 1350 C (1 to 100 h), using several techniques: SEM, TEM, STEM and Scanning AES. It was found that sulfur contents lower than 1 ppm or doping with yttrium gave flat and adherent scales. The equiaxed structure observed on Y-undoped specimens was transformed into a columnar structure when yttrium was present in the alloy. Sulfur and carbon were measured in the spalled regions of the surface where emergent grain boundaries of the substrate were present. Bending tests in the Auger device at room temperature confirmed this result: in the oxide areas cracked by bending, sulfur and carbon were found at the emergence of grain boundaries of the metal but neither sulfur nor carbon were observed in the cracked zones away from the grain boundaries of the metal. Yttrium was measured at the metal±oxide interface and in the grain boundaries of the oxide. No sulfur was found in the grain boundaries of the oxide. When yttrium was found at the metal±oxide interface, no sulfur could be detected. Chromium enrichment was observed at the metal±oxide interface in parallel with sulfur segregation but in yttrium containing alloys Cr enrichment disappeared at the same time as sulfur.

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“…The tapered bottom half of the coupon should undergo a progressive decrease in the amount of aluminum and chromium available to form protective corrosion products, while the thick, parallel-sided top half ensures that the entire coupon is not consumed during the test. This sample geometry is similar to one utilized by Al-Badairy and Tatlock [15,16], in which wedge-shaped coupons were oxidized at temperatures up to 1350°C in laboratory air. In those experiments, it was found that breakaway corrosion eventually occurred preferentially in the thinnest region of the sample due to depletion of aluminum.…”

Section: Long Term Corrosion Exposuresmentioning

confidence: 99%

Evaluation of the Corrosion Resistance of Fe–Al–Cr Alloys in Simulated Low NO x Environments

et al. 2009

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Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has led researchers to examine the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In this work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 and 700°C for short (100 h) and long (5000 h) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance during short term exposures. For longer test times, increasing the aluminum concentration improved alloy corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in slower corrosion kinetics. A general classification of the scales developed on these alloys is presented.

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Cited by 24 publications

References 3 publications

High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics

High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics

High Temperature Oxidation of UHP-Based Fe20Cr5Al Alloys

Evaluation of the Corrosion Resistance of Fe–Al–Cr Alloys in Simulated Low NO x Environments

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