Investigation of the γ′-Strengthened Quaternary Co-Based Alloys Co-Al-W-Ta

Epishin, Alexander; Petrushin, N. V.; Nolze, Gert; Gerstein, Gregory; Maier, Hans Jürgen

doi:10.1007/s11661-018-4756-3

Cited by 6 publications

(2 citation statements)

References 38 publications

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“…According to this elastic concept for rafting during creep under uniaxial 001 tensile loading the γ -phase forms rafts normal to load axis (N-rafting) if m × δ < 0 and rafts parallel to load axis (P-rafting) if m × δ > 0. N-rafting is usually observed in Ni-base alloys where δ < 0 [26,27], while P-rafting is often observed in Co-base alloys where δ > 0 [28,29]. Many experimental efforts were made to clarify the sign of m for nickel-base superalloys [16,[30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C

et al. 2021

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The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufacturing (hot isostatic pressing) as well as during technical accidents which may happen in service (overheating). High reliability of the results was achieved using specimens of different crystallographic orientations, exciting various vibration modes as well as precise measurement of the material density and thermal expansion required for modeling the resonance frequencies by finite element method. Combining the results measured in this work and literature data the elastic constants of the γ- and γ′-phases were predicted. This prediction was supported by measurement of the temperature dependence of the γ′-fraction. All data obtained in this work are given in numerical or analytical forms and can be easily used for different scientific and engineering calculations.

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Section: Introductionmentioning

confidence: 99%

Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C

et al. 2021

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“…There are many articles related to those alloys, focused on microstructure, mechanical properties, oxidation, creep resistance and the influence of quaternary and quinary alloying elements on those properties. However, in the literature data exists relatively low information about heat treatment parameters and such processes as homogenization solutionizing and aging [5][6][7][8][9][10][11][12]. Only in few publications, it is possible to find the information about the influence of alloying elements on solidus temperature of Co-Al-W alloys, and especially solvus temperature of strengthened structural elements of L1 2 type.…”

Section: Introductionmentioning

confidence: 99%

Thermal analysis of W-free Co–(Ni)–Al–Mo–Nb superalloys

Migas

Moskal

Maciąg

2020

J Therm Anal Calorim

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In this investigation, the thermal analysis of W-free cobalt-based superalloys based on Co–Al–Mo–Nb and Co–Ni–Al–Mo–Nb systems was performed. The analysis was performed at different stages of heat treatment process. The differential thermal analysis (DTA) was utilized for the determination of characteristic temperatures related to microstructural changes. First of all, the DTA analysis was carried out for discussing as-cast alloys in the temperature range of 40–1500 °C. The results showed thermal effects connected with melting and important order–disorder transition. The temperature range of 1200–1250 °C was chosen for performance of a first heat treatment operation for the investigated alloys. Specimens were annealed at selected temperature for 5 h. The microstructure of alloys after solution heat treatment was analyzed as well. Afterward, the solutionized specimens were subjected to the further thermal analysis in order to select the aging temperature according to the order–disorder transformation related to formation of γ′ phase with overall formula Co3(Al,X). Five aging variants were performed in the temperature range of 800–1000 with a step of 50 °C. After each stage of heat treatment, SEM/EDS analysis and hardness measurements were performed.

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Design of a Co–Al–W–Ta Alloy Series with Varying γ′ Volume Fraction and Their Thermophysical Properties

Volz

Xue

Bezold

et al. 2021

Metall Mater Trans A

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The γ′ volume fraction is a key parameter in precipitation-strengthened Co- and Ni-base superalloys and mainly determines the alloys’ properties. However, systematic studies with varying γ′ volume fractions are rare and the influence on thermal expansion has not been studied in detail. Therefore, a series of six Ta-containing Co-based alloys was designed with compositions on a γ–γ′ tie-line, where the γ′ volume fraction changes systematically. During solidification, Laves (C14-type) and µ (D85-type) phases formed in alloys with high levels of W and Ta. Single-phase γ or two-phase γ/γ′ microstructures were obtained in four experimental alloys after heat treatment as designed, whereas secondary precipitates, such as χ (D019-type), Laves, and μ, existed in alloys containing high levels of γ′-forming elements. However, long-term heat treatments for 1000 hours revealed the formation of the χ phase also in the former χ-free alloys. The investigation of the thermal expansion behavior revealed a significant anomaly related to the dissolution of γ′, which can be used to determine the γ′ solvus temperature with high accuracy. Compared to thermodynamic calculations, differential scanning calorimetry (DSC) and thermal expansion analysis revealed a larger increase of the γ′ solvus temperatures and a lesser decline of the solidus temperatures when the alloy composition approached the composition of the pure γ′ phase.

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Investigation of the γ′-Strengthened Quaternary Co-Based Alloys Co-Al-W-Ta

Cited by 6 publications

References 38 publications

Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C

Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C

Thermal analysis of W-free Co–(Ni)–Al–Mo–Nb superalloys

Design of a Co–Al–W–Ta Alloy Series with Varying γ′ Volume Fraction and Their Thermophysical Properties

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