Microstructure and creep performance of a multicomponent Co-based L12–ordered intermetallic alloy

Long, Fang; Baik, Sung Il; Chung, Ding-Wen; Xue, Fei; Lass, Eric A.; Seidman, David N.; Dunand, David C.

doi:10.1016/j.actamat.2020.06.050

Cited by 35 publications

(5 citation statements)

References 97 publications

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“…When alloying elements are added, the young modulus increases. This result is associated with the partitioning of Ti and Ta suggesting the influence of these elements on the elastic modulus of γ ′ phase [27,46,54]. Thus, most of the Ti and Ta atoms are consumed by the secondary phases, which cause the increase of the microhardness.…”

Section: Resultsmentioning

confidence: 99%

Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

2021

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Aiming to improve γ ′ volume fraction through alloying elements and heat treatments, the influence of the combined effect of 2 Ti and 2 Ta addition (at%) to a nominal Co-12Al-10W at.% Co-based superalloy, and the heat treatments parameters have been investigated. The Co-based alloys were manufactured by PM using mechanical alloying for powder processing, and a field-assisted sintering technique to consolidate the material. The specific study of solution temperatures and ageing times to promote the γ/γ ′ dual-phase was carried out through a complete microstructural analysis and micro and nano hardness measurements. The composition of the γ (fcc)-matrix and γ ′ (L12)-precipitates, the nanoscale properties including γ ′ volume fraction and γ/γ ′ misfit were measured as a function of increasing solution and ageing time. In the end, Ti and Ta addition to the Co-12A-10W alloy increases γ' volume fraction and thermal stability for long ageing time detecting slow coarsening.

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Section: Resultsmentioning

confidence: 99%

Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

2021

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“…For example, detrimental intermetallic phases were frequently reported to precipitate out preferentially at grain boundaries in Co‐rich alloys: γ′ phase was consumed by C36‐Laves phase at grain boundaries during the thermal exposure at 900 °C in the Co–6Ta–6V alloy [ 42 ] ; D0 19 ‐type and B2‐type phases were reported to form at grain boundaries in the Co–Al–W‐based alloys crept at 850 °C, together with adjacent L1 2 ‐precipitation denuded zones along grain boundaries. [ 79 ] Apart from these undesired formation of brittle intermetallic phases, Al segregation at grain boundaries has also been identified via atom probe analyses in a multicomponent Co‐rich L1 2 alloy, [ 80 ] whose presence increased the susceptibility to the moisture‐induced environmental embrittlement with a ductility loss. [ 81,82 ] In contrast, grain‐boundary segregating elements, such as B, Zr, and Hf, have been reported to improve the grain‐boundary cohesion and avoid brittle intergranular fracture in polycrystalline alloys [ 83 ] ; however, Bocchini et al [ 79 ] noticed the accumulated grain‐boundary damage due to phase decomposition within the crept B‐doped and Zr‐doped Co–Al–W‐based alloys.…”

Section: Discussionmentioning

confidence: 99%

L1₂‐Strengthened Co‐Rich Alloys for High‐Temperature Structural Applications: A Critical Review

et al. 2021

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Tremendous efforts have been made to accelerate the design of advanced high‐temperature structural materials, leading to the development of high‐performance Ni‐based superalloys with both superior thermal stability and creep resistance. However, further gains in the temperature capabilities are difficult to achieve due to the narrow gap between the γ′‐solvus temperature and their melting temperatures within Ni‐based superalloys. Given the 50–150 °C advantages in the melting points of Co‐rich alloys than those of the Ni‐based superalloys, as well as the discovery of L12 precipitates in the ternary Co–Al–W alloys, the L12‐strengthened Co‐rich alloys are immediately recognized as the promising candidates to be developed as next‐generation high‐temperature structural materials. Follow‐up studies indicate that they also preserve a mild segregation tendency during solidification and superior particle coarsening resistance as compared with Ni‐based superalloys. Promising research directions in the field of Co‐rich high‐temperature alloys are also discussed herein, including thermodynamic‐guided alloy design, grain boundary characteristics, and their correlations with mechanical properties, as well as unique deformation mechanisms and particle shearing configurations.

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“…As the number of multi-component L1 2 -strengthened Co-based superalloys currently developed grows, the L1 2 phase becomes more complex. [2,3,5,9,44] A huge advantage of the EMTO-CPA method is a possibility to calculate properties of multi-component compounds with relatively low computational effort. To demonstrate this the effect of alloying elements on elastic moduli for a multi-component Co-based system as a function of Ni concentration was calculated.…”

Section: Elastic Propertiesmentioning

confidence: 99%

“…To achieve this, c¢ hardened Co-based superalloys with increasingly complex multi-component composition and lower density are developed. [2][3][4][5] Recently, Liu et al [6] designed a multi-component Co-based superalloy based on machine learning results, namely, Co-36Ni-12Al-2Ti-4Ta-1W-2Cr with high c¢ solvus temperature (1266 °C), low density (8.68 g/cm 3 ), and good high-temperature oxidation resistance. However, few studies of the thermodynamic and other properties of multi-component Co-based superalloys using first-principles calculations exist.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Calculations of Elastic and Thermodynamic Properties for Multi-component Co-based Superalloys

Tang

et al. 2022

Metall Mater Trans A

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First-principles calculations were performed to investigate the elastic and thermodynamic properties for multi-component Co-based superalloy systems and explored the effect of alloying on stabilizing the γ′ phase. First, the comparisons were carried out for the γ′ phase in Co3(Al,TM) (TM being transition metals) and Ni3Al systems between the present computational results using the EMTO-CPA method and other available DFT calculations as well as experimental data. The lattice parameters, elastic constants, and Debye temperatures are consistent with experimental results and other calculations. The predicted thermodynamic properties, e.g., the Gibbs free energy, excess entropy, and linear thermal expansion coefficient, agree well with CALPHAD results, experimental results, and other available first-principles calculations. A combination of EMTO-CPA method and Debye–Grüneisen model is utilized in this work to ensure that the alloying effect on the stability of the γ′ phase in a multi-component Co-based system is captured efficiently. This could open the path for designing novel multi-component Co-based alloys based on first-principles calculation. To demonstrate this, predictions for the properties of multicomponent systems were undertaken. Our results show that Ni aids in the stabilization of the (CoNi)3(Al, Mo, Nb) phase. Graphical Abstract

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Microstructure and creep performance of a multicomponent Co-based L12–ordered intermetallic alloy

Cited by 35 publications

References 97 publications

Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

L1₂‐Strengthened Co‐Rich Alloys for High‐Temperature Structural Applications: A Critical Review

First-Principles Calculations of Elastic and Thermodynamic Properties for Multi-component Co-based Superalloys

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Microstructure and creep performance of a multicomponent Co-based L12–ordered intermetallic alloy

Cited by 35 publications

References 97 publications

Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

L12‐Strengthened Co‐Rich Alloys for High‐Temperature Structural Applications: A Critical Review

First-Principles Calculations of Elastic and Thermodynamic Properties for Multi-component Co-based Superalloys

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L1₂‐Strengthened Co‐Rich Alloys for High‐Temperature Structural Applications: A Critical Review