Two Steady-State Creep Stages in Co-Al-W-Base Single-Crystal Superalloys at 1273 K/137 MPa

Lu, Song; Antonov, Stoichko; Li, Longfei; Feng, Qiang

doi:10.1007/s11661-018-4776-z

Cited by 25 publications

(7 citation statements)

References 34 publications

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“…The base alloy1 was determined by our previous works on the single‐crystal Co–Al–W‐based superalloy (Co–7Al–8W–4Ti–1Ta (at%)), which has a comparable creep resistance with first‐generation Ni‐based single‐crystal superalloys. [ 36,37 ] Subsequently, Ni was added to expand the γ + γ′ phase region. The Co–20Ni–7Al–8W–4Ti–1Ta (at%) alloy was selected as the base alloy to further tailor other elements considering the microstructural stability (Ni, W), creep resistance (Ti, Ta, Mo, Nb), density (Al) and oxidation resistance (Cr).…”

Section: Resultsmentioning

confidence: 99%

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Data‐Driven “Cross‐Component” Design and Optimization of γ′‐Strengthened Co‐Based Superalloys

Zou

Zhang

et al. 2023

Adv Eng Mater

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The discovery of ordered γ 0 precipitates in the system of Co-Al-W-based alloys paves a new pathway for the development of hightemperature superalloys applied at high temperatures. [1,2] Compared to the widely used Ni-based superalloys, the potential for higher temperature capability is expected with Co-based superalloys due to the higher melting temperature of the major matrix component, Co. [3,4] This is very attractive for hot-end components in advanced aeroengines to further improve the fuel efficiency and mechanical properties. In addition, Co-based superalloys usually have a higher sulfide melting temperature than Ni-based superalloys, which is beneficial for the long-term service in an environment containing sulfur, such as industrial gas turbines. [4] However, due to the complexity of the actual service environment, commercial superalloys need to fulfill a variety of physical and chemical properties simultaneously, such as creep, fatigue, oxidation, corrosion, and density, which is done by tailoring the alloy composition typically comprising more than nine components. [5] Until now, the research of γ 0 -strengthened Co-based superalloys has gradually evolved from exploring alloying principles, considering individual or multiple elements, [6][7][8] to the optimization of different properties in an alloy with complex components (≥7). [9][10][11] Many researchers have demonstrated that Ni addition can significantly expand the γ þ γ 0 phase region, [12,13] which contributes to the tailoring of the microstructure by the addition of other refractory elements. Thus, a series of CoNi-based superalloys have been developed in recent years. Ta, Ti, and Nb improve the γ 0 solvus temperature (T γ 0 ) and the temperature capability, [14][15][16] while they also promote the precipitation of TCP phases, which are harmful to mechanical properties. [17,18] Cr is beneficial for improving the oxidation and corrosion resistance, but it reduces the T γ 0 and area fraction of γ 0 precipitates (A γ 0 ). [19,20] Mo, W, and Re provide good solid solution strengthening effects in Ni-based superalloys with a negative misfit (a γ 0 < a γ ). In contrast, Mo lowers the misfit of γ 0 -strengthened Co-based superalloys, which generally exhibit a positive misfit (a γ 0 > a γ ), by increasing the lattice constant of the γ matrix. This normally results in a transition of the γ 0 precipitate morphology from cuboidal to spherical, [21] which is beneficial for the microstructural stability during the long-term service process. W is the γ 0 -forming element in γ 0 -strengthened Co-based superalloys, [22] and its solution effect is lower than that in Ni-based superalloys. Moreover, the addition of W will greatly increase the density. Although Re can significantly improve the creep resistance of Ni-based superalloys by strongly

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Section: Resultsmentioning

confidence: 99%

“…Thermodynamic Analysis: All the thermodynamic calculations of phase constituent, T γ 0 , and A γ 0 = (V γ 0 ) 2/3 [37,63] in this study were performed using the PANDAT software with the commercial Co-based thermodynamic database PanCo2018.…”

Section: Methodsmentioning

confidence: 99%

Data‐Driven “Cross‐Component” Design and Optimization of γ′‐Strengthened Co‐Based Superalloys

Zou

Zhang

et al. 2023

Adv Eng Mater

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“…[118][119][120][121] Early variants of these systems have been studied with conventional wrought processing or Bridgman single crystal growth as the processing path. [122][123][124][125][126][127] The emergence of this new class of alloys was coincident with the thrust to develop new ICME tools, creating the opportunity for the design of alloys matched to PBF additive processes. [128,129] In this case study, the primary goals for alloy design were good high-temperature strength up to 1000°C (achieved by precipitation of a high volume fraction of the L1 2 phase), L1 2 solvus between 1100°C to 1250°C, high solidus and liquidus temperatures, high resistance to oxidation via alumina formation, and favorable printability.…”

Section: Limitationsmentioning

confidence: 99%

Design and Tailoring of Alloys for Additive Manufacturing

Pollock

Clarke

Babu

2020

Metall Mater Trans A

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Additive manufacturing (AM) promises a major transformation for manufacturing of metallic components for aerospace, medical, nuclear, and energy applications. This perspective paper addresses some of the opportunities for alloy and feedstock design to achieve site-specific and enhanced properties not attainable by conventional manufacturing processes. This paper provides a brief overview of the role of powders, as well as solidification and solid-state phase transformation phenomena typically encountered during fusion-based AM. Three case studies are discussed that leverage the above to arrive at microstructure control. The first case study focuses on approaches to modify the solidification characteristics by in-situ alloying. The second case study focuses on the need for concurrent design of alloys and processing conditions to arrive at the columnar to equiaxed transition during solidification. The third case study focuses on the design of a cobalt alloy for AM, with emphasis on tailoring liquid and solid state phase transformations. The need for comprehensive knowledge of processing conditions during AM, in-situ and ex-situ probing of microstructure development under AM conditions, and post-print processing, characterization, and qualification are articulated for the design of future alloys and component geometries built by AM.

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“…In recent years, the applicability of Co-base superalloys as high-temperature material has been a research topic of high interest. [1][2][3][4][5] This new class of superalloys was first reported by Lee [6] and rediscovered in 2006 by Sato et al [7] So far, the mechanical properties of Co-base alloys have been studied extensively [8][9][10][11][12][13] and they are deemed promising for applications in the intermediate-temperature regime. [14][15][16] Phase stability and high-temperature mechanical properties were significantly improved in the last years by addition of a wide range of alloying elements.…”

Section: Introductionmentioning

confidence: 99%

Correlative Nano‐Computed Tomography and Focused Ion‐Beam Sectioning: A Case Study on a Co‐Base Superalloy Oxide Scale

et al. 2019

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Herein, the capabilities of a correlative tomography approach combining laboratory nano X‐ray computed tomography, focused ion‐beam sectioning, and energy‐dispersive X‐ray spectroscopy are utilized for the characterization of multilayered oxide scales of Co‐base superalloys regarding their 3D morphology and chemical composition. The combination of complementary 3D imaging techniques allows for a precise and reliable segmentation of the pore space, oxide precipitates, and different phases of the initial material. Such information is instrumental to a microscopic understanding of oxidation in this new class of superalloys and key to improvement of oxidation resistance in the next‐generation high‐temperature materials.

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Two Steady-State Creep Stages in Co-Al-W-Base Single-Crystal Superalloys at 1273 K/137 MPa

Cited by 25 publications

References 34 publications

Data‐Driven “Cross‐Component” Design and Optimization of γ′‐Strengthened Co‐Based Superalloys

Data‐Driven “Cross‐Component” Design and Optimization of γ′‐Strengthened Co‐Based Superalloys

Design and Tailoring of Alloys for Additive Manufacturing

Correlative Nano‐Computed Tomography and Focused Ion‐Beam Sectioning: A Case Study on a Co‐Base Superalloy Oxide Scale

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