Composition and growth mechanisms of alumina scales on FeCrAl-based alloys determined by SNMS

Quadakkers, W. J.; Elschner, Andreas; Speier, W.; Nickel, H.

doi:10.1016/0169-4332(91)90069-v

Cited by 170 publications

(114 citation statements)

References 21 publications

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“…The oxidation rate of the ODS alloy was much slower than the alloy without ODS and the scale growth was limited by oxygen diffusion. The diffusion rate through a thin equiaxed outer layer formed by a cationic diffusion and an inner columnar layer grown by oxygen diffusion agrees with those obtained for O 18 diffusion in alumina doped with yttrium [95]. The transport mechanism in θ-Al2O3 has been studied by Pint [96] using 18 O/ 16 O.…”

Section: High-temperature Oxidation Of Alumina-forming Nickel-base Susupporting

confidence: 69%

Isothermal Oxidation Comparison of Three Ni-Based Superalloys

Mallikarjuna

Richards

Caley

2017

J. of Materi Eng and Perform

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Section: High-temperature Oxidation Of Alumina-forming Nickel-base Susupporting

confidence: 69%

Isothermal Oxidation Comparison of Three Ni-Based Superalloys

Mallikarjuna

Richards

Caley

2017

J. of Materi Eng and Perform

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“…3(a), according to Eq. (12). This suggests that the corresponding morphology of the P O2 (hi) surfaces is similar to each other.…”

Section: Mutual Gb Diffusion Of Both Oxygen and Aluminumsupporting

confidence: 49%

Mass transfer in polycrystalline alumina under oxygen potential gradients at high temperatures

Kitaoka

2016

J. Ceram. Soc. Japan

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The mass-transfer mechanisms of polycrystalline alumina with and without oxygen reactive elements (REs) such as Ln (Y and Lu) and Hf were investigated by evaluation of the oxygen permeability through alumina wafers, which served as a model for alumina scale, at accelerated temperatures up to 1923 K. Oxygen permeation proceeded via grain boundary (GB) diffusion of oxygen from the higher oxygen partial pressure [P O2 (hi)] surface side to the lower P O2 [P O2 (lo)] surface side, along with the simultaneous GB diffusion of aluminum in the opposite direction, maintaining the GibbsDuhem relationship. The chemical potentials, GB diffusion coefficients, and fluxes of oxygen and aluminum in alumina wafers with applied oxygen potential gradients (d® O ) were calculated from the oxygen permeability constants. The fluxes of oxygen and aluminum at the outflow side of the wafer were significantly larger than those at the inflow side. Ln and Hf segregation at the GBs selectively reduced the diffusivity of oxygen and aluminum, respectively. Thus, the mesoscopic dopant arrangements, which were selected by taking into consideration the behavior of the diffusion species and the role of dopants, enabled the alumina layers to have enhanced oxygen shielding capability at high temperatures. Furthermore, the GB diffusion data derived from the oxygen permeation experiments were compared to those for alumina scale formed by the so-called two-stage oxidation of alumina-forming alloys.

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“…[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Such insights have proven particularly useful for understanding the influence of various alloying additions on film growth, and provide a basis for improved alloy design. For example, tracer studies of Al 2 O 3 -forming alloys with and without rare earth element dopants revealed beneficial effects related to more protective, oxygen inward growth mechanisms [e.g.…”

mentioning

confidence: 99%

Tracer Film Growth Study of Hydrogen and Oxygen from the Corrosion of Magnesium in Water

Brady

Fayek

Elsentriecy

et al. 2014

J. Electrochem. Soc.

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An isotopic tracer study of the film growth mechanism for pure magnesium, AZ31B, and ZE10A (Elektron 717, E717) magnesium alloys in water at room temperature was performed. A series of individual and sequential exposures were conducted in both H 2 18 O and D 2 16 O, with isotopic tracer profiles obtained using secondary ion mass spectrometry (SIMS). The water-formed films consisted primarily of partially hydrated MgO. The SIMS sputter depth profiles indicate that H and D penetrated throughout the film and into the underlying metal, particularly for the Zr-and Nd-containing E717 alloy. Film growth for the UHP Mg involved aspects of both metal outward diffusion and oxygen/hydrogen inward diffusion. In contrast, the film on the Al-containing AZ31B alloy grew primarily by inward oxygen and inward hydrogen diffusion. The 18 O and D profiles for the film formed on E717 were the most complex, with the 18 O data most consistent with inward lattice oxygen diffusion, but the D data suggests inward, short-circuit diffusion through the film. It is speculated that preferential inward short circuit hydrogen transport may have been aided by the presence of nano Zn 2 Zr 3 particles throughout the E717 film. Such hydrogen penetration may have implications from both a corrosion resistance and hydrogen storage perspective. Magnesium alloys are of great interest because they can be used to manufacture lightweight automotive and aircraft structural materials that reduce vehicle weight and improve fuel efficiency.1-3 However, the poor corrosion resistance of Mg is a major challenge.4-6 A key contributor to the poor corrosion resistance of Mg is the inability to establish and/or maintain protective surfaces films. Surface films formed on Mg under ambient air and water conditions typically consist of mixtures of Mg(OH) 2 and MgO, with small amounts of MgCO 3 often also reported.7-12 They provide adequate protection under some circumstances, but are particularly vulnerable to disruption by salt species.The ambient corrosion of Mg differs from many corrosion-resistant structural alloy classes in that the protective surface films can become quite thick, on the order of tens to hundreds of nanometers, rather than the few nanometers typically encountered for protective films on stainless steels, for example. As such, corrosion resistance is influenced not only by classical thin film electrochemical passivity considerations, but also thermodynamic and kinetic considerations typically encountered in thick-film (> 0.5 micron range), high-temperature alloy oxidation phenomena.Isotopic tracer studies have been widely applied to studies of the high-temperature oxidation of alloys (Al, Fe, Ni, and Zr base; SiC), with significant new insights gained regarding the growth mechanism of the oxide films. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Such insights have proven particularly useful for understanding the influence of various alloying additions on film growth, and provide a basis for improved alloy design. For examp...

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Composition and growth mechanisms of alumina scales on FeCrAl-based alloys determined by SNMS

Cited by 170 publications

References 21 publications

Isothermal Oxidation Comparison of Three Ni-Based Superalloys

Isothermal Oxidation Comparison of Three Ni-Based Superalloys

Mass transfer in polycrystalline alumina under oxygen potential gradients at high temperatures

Tracer Film Growth Study of Hydrogen and Oxygen from the Corrosion of Magnesium in Water

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