On the growth of Al2O3 scales

Heuer, A. H.; Nakagawa, Takeshi; Azar, Maryam Zahiri; Hovis, D. B.; Smialek, James L.; Gleeson, Brian; Hine, Nicholas D. M.; Guhl, Hannes; Lee, H.-S.; Tangney, Paul; Foulkes, W. M. C.; Finnis, Michael W.

doi:10.1016/j.actamat.2013.07.024

Cited by 153 publications

(91 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Many of its high temperature properties are governed by the mass and charge transport along grain boundaries. Among 5 other things, this transport controls the growth rate of protective alumina scales on aluminium-containing alloys, and is consequently of profound scientific and economic interest [2,3].…”

Section: Introductionmentioning

confidence: 99%

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

et al. 2015

Self Cite

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

et al. 2015

Self Cite

View full text Add to dashboard Cite

“…(10) with P O2 = 2 © 10 4 Pa, is significantly lower than the 2),7), 8) self-diffusion data (g) 2) directly measured at the same P O2 with 18 O 2 for individual GBs in the absence of a d® O . The application of a d® O also retarded the aluminum GB diffusivity, as evident from a comparison of lines h and i.…”

Section: ¹13mentioning

confidence: 99%

“…Thus, the application of a d® O suggests there is some influence on the oxygen GB diffusivity. However, there has been only one report 2) of GB self-diffusion coefficients for aluminum in alumina in the absence of a d® O and no data with application of a d® O . One of the likely reasons for this is the lack of an appropriate radioactive tracer, such as 26 Al with a very low specific activity and an extremely long half-life of 7.2 © 10 5 years, which makes it very difficult to perform radiotracer diffusion experiments.…”

Section: Introductionmentioning

confidence: 99%

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

Kitaoka

2016

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

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.

show abstract

“…The oxygen diffusion coefficients of single GBs were recently determined by a SIMS- 18 O line profiling technique at each GB near the surface of an alumina cross section [1]. The activation energies reported for the oxygen GB diffusion in the scale tend to be larger than those for the corresponding self-diffusion data.…”

Section: Introductionmentioning

confidence: 99%

“…For scale growth by inward oxygen GB diffusion, the annihilation and production of oxygen vacancies proceed at the scale-gas and scale-metal interfaces by reactions (11.1) and (11.2), respectively [1]: Scale growth also occurs by outward aluminum GB diffusion. Aluminum vacancies are produced at the scale-gas interface by reaction (11.3) and are annihilated at the scale-metal interface by reaction (11.4) Although these reactions are expressed with holes or electrons on opposite sides, the concentrations of electrons (n) and holes (p) are related by another equilibrium constant [2]:…”

Section: Introductionmentioning

confidence: 99%

Grain Boundary Engineering of Alumina Ceramics

et al. 2018

View full text Add to dashboard Cite

Oxygen permeability through alumina wafers was evaluated at high temperatures up to 1923 K to elucidate the mass-transfer mechanisms of polycrystalline alumina and serve as a model for protective alumina film formed on heat-resistant alloys. Oxygen permeation proceeded via grain boundary (GB) diffusion of oxygen from the higher oxygen partial pressure (P O2 ) surface side to the lower P O2 surface side, along with the simultaneous GB diffusion of aluminum in the opposite direction to maintain the Gibbs-Duhem relationship. Oxygen GB diffusion coefficients in the vicinity of the P O2 (hi) surface were lower than those of oxygen GB self-diffusion without an oxygen potential gradient (dµ O ). When dµ O was applied to the wafer, the oxygen and aluminum fluxes at the outflow side of the wafer were significantly larger than those at the inflow side. Ln (Y and Lu) and Hf segregation at the GBs selectively reduced the diffusivity of oxygen and aluminum, respectively. Thus, the mesoscopic arrangements of segregating dopants, which were selected by taking into consideration the behavior of the diffusion species and the role of dopants, enabled the alumina film to have enhanced oxygen shielding capability and structural stability 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.

show abstract

On the growth of Al2O3 scales

Cited by 153 publications

References 42 publications

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

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

Grain Boundary Engineering of Alumina Ceramics

Contact Info

Product

Resources

About