Effects of Cr on the properties of multicomponent cobalt-based superalloys with ultra high <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mrow><mml:mi>γ</mml:mi><mml:mo>’</mml:mo></mml:mrow></mml:math> volume fraction

Chung, Ding Wen; Toinin, Jacques Perrin; Lass, Eric A.; Seidman, David N.; Dunand, David C.

doi:10.1016/j.jallcom.2020.154790

Cited by 45 publications

(10 citation statements)

References 61 publications

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“…Since Al is a constant across the two phases, the increase in Co concentration implies a decrease in the W concentration in the system. We have observed that W partitions towards the γ (L1 2 ) phase and stabilizes it, which explains how the equilibrium precipitate size is smaller when there is a higher Co concentration [6].…”

Section: Discussionmentioning

confidence: 71%

“…)/γ (L1 2 ) two-phase region to Ni-based superalloys, the chemistry is quite different, and the existing body of knowledge of Ni-based superalloys often cannot be directly transferred to Co-based superalloys. Current research has been focused on better understanding how different factors influence the equilibrium microstructure, specifically the effects of alloying elements [16,19,4,6] and external stresses [21,5].…”

Section: Introductionmentioning

confidence: 99%

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Active Learning Sensitivity Analysis of $γ^\prime$(L1$_2$) Precipitate Morphology of Ternary Co-Based Superalloys

Tso¹,

Wu²,

Seidman³

et al. 2023

Preprint

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To better understand the equilibrium γ (L1 2 ) precipitate morphology in Co-based superalloys, a phase field modeling sensitivity analysis is conducted to examine how four phase-field parameters [initial Co concentration (c 0 ), double-well barrier height (ω), gradient energy density coefficient (κ), and lattice misfit strain ( misfit )] influence the γ (L1 2 ) precipitate size and morphology. Gaussian Process Regression (GPR) models are used to fit the sample points and to generate surrogate models for both precipitate size and morphology. In an Active Learning approach, a Bayesian Optimization algorithm is coupled with the GPR models to suggest new sample points to calculate and efficiently update the models based on a reduction of uncertainty. The algorithm has a user-defined objective, which controls the balance between exploration and exploitation for new suggested points. Our methodology provides a qualitative and quantitative relationship between the γ (L1 2 ) precipitate size and morphology and the four phase-field parameters, and concludes that the most sensitive

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Section: Discussionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Active Learning Sensitivity Analysis of $γ^\prime$(L1$_2$) Precipitate Morphology of Ternary Co-Based Superalloys

Tso¹,

Wu²,

Seidman³

et al. 2023

Preprint

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show abstract

“…However, Zhou et al (2018) proposed that the addition of the Mo element can change interfacial energy, thus reducing the coarsening rate of the γ′ phase, and improving the high temperature stability of superalloys. In addition, Cr elements prefer to be distributed in the γ phase matrix (Chung et al, 2020), and a large amount of Cr can reduce the volume fraction of γ′ phase in superalloys, although it can greatly improve oxidation resistance of superalloys (Chen et al, 2019;Chung et al, 2020;Li W. et al, 2020). By studying the microstructure of superalloys with different Cr contents, Ng et al (2020) showed that higher Cr content leads to precipitation of harmful μ phase and deteriorates the mechanical properties of superalloys.…”

Section: Introductionmentioning

confidence: 99%

Coarsening Evolution of γ′ Phase and Failure Mechanism of Co-Ni-Al-Ti-Based Superalloys During Isothermal Aging

et al. 2022

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Novel Co-based superalloys, as potentially ideal aero-engine hot section materials, have a higher temperature bearing capacity and better oxidation resistance than Ni-based superalloys. Coarsening evolution of γ′ phase and failure mechanism of Co-Ni-Al-Ti-based superalloys during the isothermal aging process at 1073 K were investigated using multiple characterizations and testing methods. The results show that γ′ phase is uniformly distributed on the γ phase matrix, and coarsening with the increase in isothermal aging time, which results in a decrease in maximum tensile strength. Furthermore, Mo element is preferred to distribute in γ′ phase and provides stronger solution strengthening effect than Cr element, which determines more excellent mechanical properties of 2Mo superalloy than that of 2Cr superalloy. The coarsening rate of γ′ phase in the 2Cr superalloy is significantly higher than that in the 2Mo superalloy. Grain boundary failure is dominant in isothermal aging, and the cracks nucleate and expand along the vertical direction of loading stress on the grain boundary. The current work suggests that the coarsening of the γ′ phase, reduction in the volume fraction of γ′ phase, and formation of ′-precipitate depleted zone (PDZ) near the grain boundary during aging controls the deterioration of mechanical properties in Co-Ni-Al-Ti-based superalloys.

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“…On the other hand, cobalt-based superalloy with et al, 2003), (Long et al, 2013), (Yan et al, 2016), (Farotade and Popoola, 2017) g /g ¨structure has good wear resistance, oxidation and melting temperatures higher than the nickel-based superalloy. Chung et al (2020b) reported that the addition of chromium to cobaltbased superalloys improves the oxidation resistance but adversely affects the creep performance. The superalloy has poor creep resistance, limiting the superalloy's usage in highstress applications (Jokisaari et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Recent advances of high entropy alloys for aerospace applications: a review

Dada

Popoola

Mathe

2021

WJE

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Purpose This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential alternatives to nickel superalloys for gas turbine applications. Understandings of the laser surface modification techniques of the HEA are discussed whilst future recommendations and remedies to manufacturing challenges via laser are outlined. Design/methodology/approach Materials used for high-pressure gas turbine engine applications must be able to withstand severe environmentally induced degradation, mechanical, thermal loads and general extreme conditions caused by hot corrosive gases, high-temperature oxidation and stress. Over the years, Nickel-based superalloys with elevated temperature rupture and creep resistance, excellent lifetime expectancy and solution strengthening L12 and γ´ precipitate used for turbine engine applications. However, the superalloy’s density, low creep strength, poor thermal conductivity, difficulty in machining and low fatigue resistance demands the innovation of new advanced materials. Findings HEAs is one of the most frequently investigated advanced materials, attributed to their configurational complexity and properties reported to exceed conventional materials. Thus, owing to their characteristic feature of the high entropy effect, several other materials have emerged to become potential solutions for several functional and structural applications in the aerospace industry. In a previous study, research contributions show that defects are associated with conventional manufacturing processes of HEAs; therefore, this study investigates new advances in the laser-based manufacturing and surface modification techniques of HEA. Research limitations/implications The AlxCoCrCuFeNi HEA system, particularly the Al0.5CoCrCuFeNi HEA has been extensively studied, attributed to its mechanical and physical properties exceeding that of pure metals for aerospace turbine engine applications and the advances in the fabrication and surface modification processes of the alloy was outlined to show the latest developments focusing only on laser-based manufacturing processing due to its many advantages. Originality/value It is evident that high entropy materials are a potential innovative alternative to conventional superalloys for turbine engine applications via laser additive manufacturing.

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Effects of Cr on the properties of multicomponent cobalt-based superalloys with ultra high γ’ volume fraction

Cited by 45 publications

References 61 publications

Active Learning Sensitivity Analysis of $γ^\prime$(L1$_2$) Precipitate Morphology of Ternary Co-Based Superalloys

Active Learning Sensitivity Analysis of $γ^\prime$(L1$_2$) Precipitate Morphology of Ternary Co-Based Superalloys

Coarsening Evolution of γ′ Phase and Failure Mechanism of Co-Ni-Al-Ti-Based Superalloys During Isothermal Aging

Recent advances of high entropy alloys for aerospace applications: a review

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