The Effect of Heat Treatment on the Oxidation Resistance of Cobalt-Based Superalloys

Moffat, James; Whitfield, Tamsin; Christofidou, Katerina A.; Pickering, Ed; Jones, Nicholas; Stone, H.J.

doi:10.3390/met10020248

Cited by 6 publications

(3 citation statements)

References 40 publications

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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%

“…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. Xiao et al [24] studied the cyclic oxidation behavior of Pt-modified γ' nanocrystalline coating at 1150 • C and confirmed that the nanocrystalline structure promoted the formation of α-Al 2 O 3 oxide coating with lower Pt and Al contents, which improved the anti-spalling performance.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

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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“…Applications of these alloys include gas turbines, aircraft engines, and chemical reactors [4][5][6]. The Co-based superalloys are often alloyed with chromium to provide oxidation resistance [7,8]. The superalloys alloyed with Cr form a compact chromia scale (Cr 2 O 3 ) on their surface.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Al-Co Alloys at High Temperatures

et al. 2020

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In this work, the high temperature oxidation behavior of Al71Co29 and Al76Co24 alloys (concentration in at.%) is presented. The alloys were prepared by controlled arc-melting of Co and Al granules in high purity argon. The as-solidified alloys were found to consist of several different phases, including structurally complex m-Al13Co4 and Z-Al3Co phases. The high temperature oxidation behavior of the alloys was studied by simultaneous thermal analysis in flowing synthetic air at 773–1173 K. A protective Al2O3 scale was formed on the sample surface. A parabolic rate law was observed. The rate constants of the alloys have been found between 1.63 × 10−14 and 8.83 × 10−12 g cm−4 s−1. The experimental activation energies of oxidation are 90 and 123 kJ mol−1 for the Al71Co29 and Al76Co24 alloys, respectively. The oxidation mechanism of the Al-Co alloys is discussed and implications towards practical applications of these alloys at high temperatures are provided.

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Surveying the Effects of Aging a High C-Containing Co-Based Superalloy From the As-Cast and Solution Heat-Treated Conditions

Moffat,

Christofidou,

Pek

et al. 2024

Metall Mater Trans A

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The microstructure of the high carbon-containing cobalt-based superalloy, Co-101, has been studied in the as-cast state and following a variety of heat treatments. In the as-cast state both M7C3 and Mo-rich M23C6 carbides were observed in the interdendritic regions. After thermal exposure at temperatures between 1000 °C and 1250 °C for 1, 10, and 100 hours, the M7C3 interdendritic carbide network was observed to transform into a Mo-lean M23C6 carbide. These changes were rationalized with thermodynamic calculations. The carbide transformation liberated carbide-forming elements that resulted in the precipitation of intragranular carbides in the dendritic regions at temperatures below 1150 °C. These carbides in the cast-aged material preferentially formed at the dendrite peripheries early during exposure, leading to wide particle size distributions. Peak hardness in the cast-aged material was attained within the first 10 hours of exposure and softening was observed thereafter. After solution heat treating at 1250 °C for 10 hours, the microstructure of Co-101 comprised an M23C6 interdendritic carbide network and solid solution dendrites supersaturated with carbide-forming elements. Subsequent aging of this microstructure for 100 hours at 900 °C led to a high number density and narrow particle size distribution of intragranular carbides. The characteristics of these carbides in the solution-aged material resulted in greater hardness, which was retained for longer durations of exposure, than the cast-aged specimens.

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The Effect of Heat Treatment on the Oxidation Resistance of Cobalt-Based Superalloys

Cited by 6 publications

References 40 publications

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

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

Oxidation of Al-Co Alloys at High Temperatures

Surveying the Effects of Aging a High C-Containing Co-Based Superalloy From the As-Cast and Solution Heat-Treated Conditions

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