Intermediate Temperature Internal Oxidation in Fourth Generation Ru-bearing Single-Crystal Nickel-base Superalloys

Edmonds, Ian M.; Evans, Hugh E.; Jones, C.N.; Broomfield, Robert W.

doi:10.1007/s11085-007-9085-7

Cited by 22 publications

(12 citation statements)

References 22 publications

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“…Evidence of slow-growing protective spinels has been previously reported [19]. The chromite formed here showed slower growth kinetics than the titanium-doped Cr2O3 formed at bar pressure.…”

Section: Discussionsupporting

confidence: 73%

The effect of elevated air pressure on the oxidation properties of the nickel-based superalloy, RR1000, at 650°C with different surface modifications

Reynolds

Taylor

Child

et al. 2017

Materials at High Temperatures

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Samples of RR1000 with differing grain size and surface finish have been exposed to air at different pressures. Specimens were exposed for 4000 hours at 650°C with some exposed to atmospheric pressure air and some exposed to air at 40 bar pressure. Samples exposed to elevated pressure formed a surface layer of NiCr2O4 whereas that formed on samples tested at 1 bar pressure was chromia. The surface layer formed at 40 bar pressure was thinner than that a 1 bar pressure. At 1 bar pressure, some samples exhibited regions of convoluted buckled oxides but no spallation. In adjacent regions of planar oxides, spallation did occur. For the latter case, an estimate of 6 Jm-2 for the interfacial fracture energy has been made. None of the specimens tested at 40 bar pressure exhibited oxide spallation.

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“…Evidence of slow-growing protective spinels has been previously reported [19]. The chromite formed here showed slower growth kinetics than the titanium-doped Cr2O3 formed at bar pressure.…”

Section: Discussionsupporting

confidence: 73%

The effect of elevated air pressure on the oxidation properties of the nickel-based superalloy, RR1000, at 650°C with different surface modifications

Reynolds

Taylor

Child

et al. 2017

Materials at High Temperatures

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“…As discussed elsewhere [13,17], the uncoated Ru-bearing alloys exhibit sub-surface pit formation during oxidation at 750 o C as is shown in Figure 6. The aluminized versions of these alloys show no evidence of such attack at this temperature as can be seen from Figure 7.…”

Section: Characterization Of Oxidesmentioning

confidence: 52%

Oxidation and Coating Evolution in Aluminized Fourth Generation Blade Alloys

Edmonds¹,

Evans²,

Jones³

2008

Superalloys 2008 (Eleventh International Symposium)

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Oxidation tests have been undertaken in air on two aluminized experimental fourth-generation Ni-based superalloys containing, respectively, 3 and 5 wt.% Ru, in order to detail the effect of Ru on oxidation characteristics and coating evolution. A Ru-free, aluminide coated third generation alloy (CMSX-10K) was also included in the test programme which used temperatures covering the range 750-1100 o C.Aluminization has been shown to effectively minimize the effect of alloy chemistry on oxidation rate constants over the timescales studied, when compared to the uncoated substrates. Aluminization also prevents the formation of internal oxidation pits in the coated Ru-bearing alloys after oxidation at 750°C. Increasing Ru marginally decreased the mass-gain due to oxidation of the three aluminized alloys at all temperatures. At 750°C the rate of oxidation of aluminized specimens was controlled not by the formation of aluminas but by that of the spinel phase Ni(Al,Cr) 2 O 4 . Interestingly, each of the three aluminized alloys produced a different coating -substrate microstructural interaction after exposure at 1100°C, with Ru increasing the propensity for secondary reaction zone (SRZ) formation. SRZs are characterized by a weak high angle boundary which can lead to localized coating loss (and hence increased section loss). Ru also underwent long range diffusion, concentrating in the β-NiAl phase in solution, and where SRZ was present resulted in the precipitation of β2-RuAl within the γ' SRZ matrix in addition to the topologically close-packed precipitates (TCPs).

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“…Ru, which is added to fourth generation Ni-base superalloys, would be a good example. The effects of Ru on the oxidation resistance of Ni-base superalloys are still controversial [1,2,25,26,[35][36][37] ; however, some studies [25,26] reported that Ru-containing Ni-base superalloys show inferior oxidation resistance than the previous generation alloys, although Ru provides excellent creep properties and microstructure stability at an elevated temperature. [38,39] A prediction or model of the oxidation behavior, based on alloy composition, should also correspond to such changes.…”

Section: Discussionmentioning

confidence: 99%

A New Oxide Morphology Map: Initial Oxidation Behavior of Ni-Base Single-Crystal Superalloys

Suzuki

Kawagishi

Yokokawa

et al. 2011

Metall Mater Trans A

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Predictions for oxidation behavior of Ni-base superalloys become more difficult than before because of the complex alloy composition. In this study, we focus on the initial oxidation behavior of Ni-base superalloys, and we suggest a new diagram to predict the initial oxide morphology of Ni-base superalloys with 63 binary, ternary, and multicomponent Ni-base single-crystal superalloys at 1373 K (1100°C). As a comparison of observed and calculated weight changes after one cycle at 1373 K (1100°C) obtained by a regression analysis, 63 alloys demonstrated two distinct behaviors, which are divided heretofore into group A and group B. Microstructural observation revealed that an oxide layer in the group A alloys consists of Al 2 O 3 and/or spinel or complex oxide, whereas an oxide layer in the group B alloys consists of a thick NiO layer with an Al 2 O 3 internal subscale. Thermodynamic properties can reflect more effects of alloy elements in Ni-base superalloys, and Al and Cr activities, calculated by Thermo-Calc, were used as factors to predict initial oxidation morphology. Groups A and B alloys can clearly be divided according to Al and Cr activities. This was suggested as a new diagram to predict the initial oxide morphology of Ni-base superalloys, and possibly it can apply for any generation of Ni-base superalloys.

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Intermediate Temperature Internal Oxidation in Fourth Generation Ru-bearing Single-Crystal Nickel-base Superalloys

Cited by 22 publications

References 22 publications

The effect of elevated air pressure on the oxidation properties of the nickel-based superalloy, RR1000, at 650°C with different surface modifications

The effect of elevated air pressure on the oxidation properties of the nickel-based superalloy, RR1000, at 650°C with different surface modifications

Oxidation and Coating Evolution in Aluminized Fourth Generation Blade Alloys

A New Oxide Morphology Map: Initial Oxidation Behavior of Ni-Base Single-Crystal Superalloys

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