Growth mechanism of Cr2O3 scales: oxygen and chromium diffusion, oxidation kinetics and effect of yttrium

Tsai, Shirley C.; Huntz, A.M.; Dolin, C.

doi:10.1016/0921-5093(96)10173-8

Cited by 190 publications

(116 citation statements)

References 22 publications

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“…This illustrates oxygen transport taking place through the external oxide to form new oxide at the alloy/ oxide interface, but at the same time new oxide forms at the gas/oxide interface, which relies on outward cation diffusion. Indeed, these findings agree with other studies, which previously revealed countercurrent mechanisms in growing chromia scales, 16,17,21,22 which is consistent with the observations that the Cr 2 O 3 normally grows through outward cationic growth (i.e., p-type behavior). 16 Therefore, the oxide grows through simultaneous countercurrent transport of inwardly diffusing oxygen anions and outwardly diffusing titanium and chromium cations.…”

Section: Classic Oxidationsupporting

confidence: 83%

“…Importantly, the coefficients here agree with the apparent oxygen diffusion coefficients measured for Cr 2 O 3 scales grown on Ni-30Cr alloys at the same temperature. 17 …”

Section: Oxygen Tracer Diffusion Coefficient In External Oxidementioning

confidence: 99%

“…[10][11][12][13][14] Energy-dispersive x-ray analyses showed that the overall oxide morphology from the external scale to internal oxides of Cr 2 O 3 /TiO 2 in the outer scale to Al 2 O 3 internally agrees with the expected thermodynamic behavior; however, and in contrast to the thermodynamic predictions, the alloy formed an outer layer of TiO 2 , believed to be at the expense of its oxidation resistance. 14,15 Cationic diffusion is inferred from the known transport mechanisms for Cr 2 O 3 growth 16,17 and from the fact that titanium must diffuse outwards to form above the outer scale. This requires titanium diffusion through the chromia and an adequate solubility of the chromium sublattice.…”

Section: Classic Oxidationmentioning

confidence: 99%

“…An analysis used the isotopic fraction v of the oxygen isotopes distribution, as this mitigates the spurious variations in signal intensity due to sample topography, localized charging, and instrumental factors. Neglecting the contribution from 17 O À , the isotopic fraction was calculated as:…”

Section: Oxygen Tracer Diffusion Coefficient In External Oxidementioning

confidence: 99%

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Oxidation of a Commercial Nickel-Based Superalloy under Static Loading

Foss

Hardy

Child

et al. 2014

JOM

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The current demands of the aviation industry for increased gas-turbine efficiency necessitate higher turbine entry temperatures, requiring that alloys exhibit superior oxidation resistance. The synergistic effects of oxidation and mechanical stresses pose a complex issue. The purpose of the current research was to examine the effects of stress on the oxidation and oxygen transport in a commercial nickel-based superalloy. Fine grain RR1000 in both polished and shot-peened conditions was studied for classic (zero load) and statically loaded conditions using integrated two-stage isotopic tracing combined with focusedion-beam secondary ion mass spectrometry (FIB-SIMS). Cr 2 O 3 external oxide formed with semicontinuous TiO 2 above and below. Preferential grain boundary Al 2 O 3 internal oxide formation, c¢-dissolution, and recrystallization occurred subsurface. Oxidation mechanisms were dominated by anionic/cationic growth in the external oxide with inward oxygen transport, initially through the partially unprotective external oxide, then along internal oxide/ alloy interfaces. Loading did not influence the oxidation products formed but did bring about expedited oxidation kinetics and changes to the oxide morphology. The oxygen diffusivity D O * (910 À13 cm 2 s À1 ) ranged from 0.39 for the polished alloy to 3.7 for the shot-peened condition under compressive stress. Arguably, the most significant effects took place in the subsurface regions. Increased oxidation kinetics were attributed to the development of fast cation diffusion paths as the alloy deformed by creep.

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Section: Classic Oxidationsupporting

confidence: 83%

“…Importantly, the coefficients here agree with the apparent oxygen diffusion coefficients measured for Cr 2 O 3 scales grown on Ni-30Cr alloys at the same temperature. 17 …”

Section: Oxygen Tracer Diffusion Coefficient In External Oxidementioning

confidence: 99%

Section: Classic Oxidationmentioning

confidence: 99%

Section: Oxygen Tracer Diffusion Coefficient In External Oxidementioning

confidence: 99%

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Oxidation of a Commercial Nickel-Based Superalloy under Static Loading

Foss

Hardy

Child

et al. 2014

JOM

View full text Add to dashboard Cite

show abstract

“…Using the values of the oxygen partial pressure from the work of Huntz et al [1], and the diffusion coefficients from the work of Tsai et al [23], it is possible to calculate the values of k s for Cr 2 O 3 , 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64Fe 2 O 3 and M 3 O 4 at 1050 °C. Finally, using eq.…”

Section: Growth Modelmentioning

confidence: 99%