Chromia layer growth on a Ni-based superalloy: Sub-parabolic kinetics and the role of titanium

Cruchley, Sam; Evans, Hugh E.; Taylor, M.P.; Hardy, Mark; Stekovic, Svjetlana

doi:10.1016/j.corsci.2013.05.016

Cited by 150 publications

(108 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Cr concentration in both alloys was lower than that of RR1000, while Ti, often linked to poor oxidation performance, [17] was marginally increased. Therefore, the oxidation performance of the alloys was expected to suffer.…”

Section: Discussionmentioning

confidence: 98%

“…In particular, the relatively low Cr:Ti ratio of these alloys would be expected to reduce the oxidation resistance to below that of RR1000, as Ti is known to increase the vacancy concentration within the protective chromia scale. [17] Therefore, the oxidation performance of these alloys at 800°C was evaluated in detail, in order to understand their response to environmental factors.…”

Section: Alloy Design Methodologymentioning

confidence: 99%

“…Consequently, they were believed to be TiN, in line with features seen in similar superalloys. [17] The thickness of the zone affected by TiN precipitation was found to be similar in both alloys, and therefore it was not included in the overall oxidation damage analysis presented in Figure 6. Critically, both alloys displayed oxidation damage that was superior to that observed in RR1000, details of which can be found in the works of Taylor et al [31] and Cruchley et al [32] D. Microstructural Stability…”

Section: Oxidationmentioning

confidence: 99%

See 2 more Smart Citations

On the Effect of Nb on the Microstructure and Properties of Next Generation Polycrystalline Powder Metallurgy Ni-Based Superalloys

Christofidou

Hardy

et al. 2018

Metall Mater Trans A

View full text Add to dashboard Cite

The effect of Nb on the properties and microstructure of two novel powder metallurgy (P/M) Ni-based superalloys was evaluated, and the results critically compared with the Rolls-Royce alloy RR1000. The Nb-containing alloy was found to exhibit improved tensile and creep properties as well as superior oxidation resistance compared with both RR1000 and the Nb-free variant tested. The beneficial effect of Nb on the tensile and creep properties was due to the microstructures obtained following the post-solution heat treatments, which led to a higher γ′ volume fraction and a finer tertiary γ′ distribution. In addition, an increase in the anti-phase-boundary energy of the γ′ phase is also expected with the addition of Nb, further contributing to the strength of the material. However, these modifications in the γ′ distribution detrimentally affect the dwell fatigue crack-growth behavior of the material, although this behavior can be improved through modified heat treatments. The oxidation resistance of the Nb-containing alloy was also enhanced as Nb is believed to accelerate the formation of a defect-free Cr2O3 scale. Overall, both developmental alloys, with and without the addition of Nb, were found to exhibit superior properties than RR1000.

show abstract

Section: Discussionmentioning

confidence: 98%

Section: Alloy Design Methodologymentioning

confidence: 99%

Section: Oxidationmentioning

confidence: 99%

See 1 more Smart Citation

On the Effect of Nb on the Microstructure and Properties of Next Generation Polycrystalline Powder Metallurgy Ni-Based Superalloys

Christofidou

Hardy

et al. 2018

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…[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%

Oxidation of a Commercial Nickel-Based Superalloy under Static Loading

Foss

Hardy

Child

et al. 2014

JOM

View full text Add to dashboard Cite

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.

show abstract

“…The high temperature oxidation resistance of chromia forming nickel-base superalloys has been recorded by number of authors [70] [83] [84]. The purpose of chromium addition to nickel-base superalloys is to form thermodynamically stable and protective chromia scale (Cr2O3).…”

Section: Oxidation Of Alloysmentioning

confidence: 99%