Kinetic and Metallography Study of the Oxidation at 1250 °C of {Co+Ni}-Based Superalloys Containing Ti to Form MC Carbides

Berthod, Patrice; Wora, Synthia Annick Ozouaki; Aranda, Lionel; Medjahdi, Ghouti; Etienne, Erwan

doi:10.3390/met12010010

Cited by 5 publications

(4 citation statements)

References 20 publications

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“…By isolating chromia a little from the air during the oxidation tests, it can be thought that chromia volatilization was thus a little prevented, as this was recently encountered with a TiO 2 developed on the outer side of chromia for Co and Ni alloys containing Ti. [ 33 ] The degradation of the Ni‐richest alloys of this study by oxidation was not significantly worse than in the case of the oxidation‐resistant Ni–30Cr alloy taken in reference. There are only a limited deleterious role of Ta and no real effect of the added Co.…”

Section: Discussionmentioning

confidence: 72%

Oxidation at 1250°C of {Cr, Ta}‐rich carbides‐strengthened {Ni, Co}‐based alloys

Berthod

Gomis

Aranda

et al. 2022

Materials & Corrosion

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Thermogravimetry tests were performed for 70 h at 1250°C in the air for six TaC-strengthened alloys with different values of the Ni/Co ratio. The oxidation and chromia volatilization rates were specified, and the formed oxides were characterized. Metallographic observations show that the alloys rich in Ni (from ≈70 to ≈25 wt.% Ni) stayed chromia-forming until the end of the 70 h. In contrast, catastrophic oxidation locally started in the case of the Co-based alloys, which are too poor in Ni. The numerical exploitation of the mass gain files was done taking into account the mass loss induced by the chromia volatilization phenomenon. Results clearly showed a regular increase in oxidation parabolic constant when Ni is more and more replaced by Co. K E Y W O R D S high-temperature oxidation, mass gain kinetics, post-mortem characterization, superalloys | INTRODUCTIONCarbides are hard particles on which the hightemperature mechanical resistance of some superalloys is based. This principle of reinforcement by a second phase was the main way used for the earliest superalloys. These ones appeared near the middle of the last century. In their case, most of the strengthening particles were chromium carbides. [1,2] More recent cast polycrystalline equiaxed superalloys are still reinforced by carbides. In many cases, these carbides are of various types in the same alloy: chromium carbides, carbides involving other elements, such as Ta, Ti, Nb, and so forth. Some of these alloys contain MC carbides among their carbide populations. These ones can be based on Ni [3][4][5] or on Co. [6][7][8][9] MC carbides can be also present in the oriented microstructures of directionally solidified (DS) Ni-based [10] or Co-based [11] superalloys. MC can be obtained as the single carbide phase present in the microstructure of Co-based alloys [12,13] if the C and M weight contents are well rated. By respecting this condition, alloys containing exclusively eutectic TaC, [14] TiC, [15] or NbC, [16] and even HfC, [17] may be successfully produced. These MC carbides are mainly localized in the grain boundaries and between dendrites. By basing the mechanical properties on these eutectic refractory carbides, one may obtain particularly creep-resistant polycrystalline superalloys for possible uses in a wide range of elevated temperatures, extending to 1200 and maybe 1250°C. [18] Indeed, these high temperatures are still about 100°C below the start of the melting of these alloys but MC carbides are still present in their microstructures. This is a decisive advantage by comparison with γ/γ' nickel-based single crystals. Indeed, these later alloys lose their reinforcing particles above 1100°C. MC-reinforced alloys are also superior to superalloys strengthened by carbides of more classical type: for example, Cr 7 C 3 or (Cr,W) 23 C 6 ) also disappear at such high temperatures. In addition, one may also point out that the conventionally cast MCstrengthened superalloys can be used as structural materials for geometrically complex components for working at ...

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Section: Discussionmentioning

confidence: 72%

Oxidation at 1250°C of {Cr, Ta}‐rich carbides‐strengthened {Ni, Co}‐based alloys

Berthod

Gomis

Aranda

et al. 2022

Materials & Corrosion

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“…It is well known that oxidation resistance is one of the most important aspects of nickel-based superalloys since poor oxidation resistance hinders their possible applications at high temperatures [12]. The oxidation behaviors of advanced nickel-based superalloys at temperatures higher than 700 • C have been studied extensively [19][20][21][22]. Brenneman et al [19] studied the oxidation behavior of GTD111 superalloy at 900 • C in air and concluded that the oxidation resistance was provided by the continuous dense Cr 2 O 3 oxide band, rather than the discontinuous Al 2 O 3 oxide layer.…”

Section: Introductionmentioning

confidence: 99%

“…Liu et al [23] studied the oxidation behavior of single-crystal nickel-based superalloy DD32 in air at 900 • C and 1000 • C and found that two oxidation steps appeared in the oxidation kinetics, which were controlled by NiO growth and Al 2 O 3 growth, respectively. Berthod et al [20] studied the oxidation behavior of six (Co + Ni)-based Cr-rich alloys with different Co/Ni ratios at 1250 • C and concluded that the higher the Ni content, the better the oxidation resistance of the alloys. Moffat et al [21] studied the oxidation behavior of a carbide network in low or high carbon Co-based superalloys at 1000 • C. They concluded that the carbide in low carbon alloys is more soluble than that in high carbon alloys, thus reducing the continuity of the carbide network and ultimately leading to an increase in the thickness of the oxide layer.…”

Section: Introductionmentioning

confidence: 99%

Oxidation Property of a Fourth-Generation Powder Metallurgy FGH4108 Nickel-Based Superalloy

Zhao

Wang

et al. 2023

Metals

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Isothermal oxidation kinetics of a fourth-generation powder metallurgy FGH4108 nickel-based superalloy is investigated at 800 °C to 1100 °C by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). At 800 °C and 900 °C, the oxidation kinetic curves of the FGH4108 superalloy follow parabolic law. At 1000 °C, the oxidation kinetic curve follows cubic law. At 1100 °C, the oxidation kinetic curve has two distinct parts: the first part follows a parabolic law, and the second one obeys a linear law. Cross-sectional morphologies and elemental distributions show that the oxide film consists of two parts at 800 °C: the outer layer is a continuous dense protective Cr2O3 oxide film, and the inner layer is a discontinuous Al2O3 oxide layer. At 900–1100 °C, the oxides consist of three layers: the outermost is the oxides of Cr2O3 and TiO2, the middle is a continuous oxide of Al2O3, and the innermost is dotted oxides of TiO2. The thickness of the inner TiO2 oxide layer increases with the increase of oxidation temperature. On this basis, the oxidation behavior of the FGH4108 superalloy at high temperatures is confirmed to be controlled by the diffusion of Cr, Al, Ti, and O. From the aspect of oxidation resistance, the long-term service temperature of the FGH4108 superalloy should not exceed 1000 °C.

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“…Among them there are applications that combine the complex geometry of the concerned components (excluding single crystals and oxide dispersion strengthened superalloys), the need of high resistance against corrosion by hot aggressive melts in absence of protective coatings (excluding alumina-forming superalloys), sustainability of the reinforcing particles even at 1100 • C and slightly more (excluding γ -reinforced alloys), and not too high density (excluding heavy refractory alloys). The reinforcement of cobalt-based [1,2,7] and nickel-based [4,8,9] conventionally cast chromium-rich alloys with MC carbides such as TaC, HfC or TiC is one of the ways new developments and application prospects to superalloys of this family are offered. The refractory monocarbides list can be enriched by ZrC, which may be present in solidified alloys with a morphology similar to the MC carbides cited above [10].…”

Section: Introductionmentioning

confidence: 99%

Creep and Oxidation Behaviors of 25 wt.% Cr–Containing Nickel-Based Alloys Reinforced by ZrC Carbides

Berthod

Tlili

2022

Crystals

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Three alloys based on nickel, rich in chromium due to their oxidation resistance at high temperature and containing ZrC carbides for their mechanical reinforcing against creep, were elaborated by foundry. After control of their as-cast microstructures, these alloys were subjected at 1100 °C to flexural creep and to oxidation in air. Script-like ZrC carbides were obtained in the interdendritic spaces, forming a eutectic compound with a part of the matrix. One of the alloys additionally contained Cr7C3 eutectic carbides. By comparison with a Ni–Cr–C reference alloy with similar contents in Cr and C, the three alloys demonstrated a much better creep resistance for the same conditions of stress and temperature. However, their oxidation rates were much greater than for the reference alloy. In contrast with the chromia-forming reference alloy, several kinds of oxides formed in the case of the three alloys, as NiCr2O4 spinel and oxides involving zirconium. A significant inward interdendritic oxidation progression was noticed for the three studied alloys. To benefit from the interesting creep resistance of these alloys for long sustainability in service, it appears necessary to significantly improve their oxidation behavior.

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Kinetic and Metallography Study of the Oxidation at 1250 °C of {Co+Ni}-Based Superalloys Containing Ti to Form MC Carbides

Cited by 5 publications

References 20 publications

Oxidation at 1250°C of {Cr, Ta}‐rich carbides‐strengthened {Ni, Co}‐based alloys

Oxidation at 1250°C of {Cr, Ta}‐rich carbides‐strengthened {Ni, Co}‐based alloys

Oxidation Property of a Fourth-Generation Powder Metallurgy FGH4108 Nickel-Based Superalloy

Creep and Oxidation Behaviors of 25 wt.% Cr–Containing Nickel-Based Alloys Reinforced by ZrC Carbides

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