Coarsening behaviour and interfacial structure of γ′ precipitates in Co-Al-W based superalloys

Vorontsov, V.A.; Barnard, J. S.; Rahman, K.M.; Yan, Hui; Midgley, Paul A.; Dye, David

doi:10.1016/j.actamat.2016.08.023

Cited by 91 publications

(13 citation statements)

References 39 publications

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“…A similar reaction yielding to the phases Moss, Mo3Si and Mo5SiB2 develops during the compaction of the pre-alloyed Mo-9Si-8B powders (Figure 8b), which is also in good agreement with the respective phase diagram [28]. The type of microstructures we achieved for compact V-Si-B and Mo-Si-B materials appear similar to the microstructure concepts of other multi-phase high temperature materials, like cobalt-based or nickel-based superalloys and Co/Ni model superalloys [56][57][58]. In all cases intermetallic particles are incorporated in a solid solution matrix.…”

Section: Microstructure Of Compact Materialssupporting

confidence: 71%

“…The type of microstructures we achieved for compact V-Si-B and Mo-Si-B materials appear similar to the microstructure concepts of other multi-phase high temperature materials, like cobalt-based or nickel-based superalloys and Co/Ni model superalloys [56][57][58]. In all cases intermetallic particles are incorporated in a solid solution matrix.…”

Section: Microstructure Of Compact Materialsmentioning

confidence: 67%

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Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Krüger

Schmelzer

Helmecke

2016

Metals

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V-Si-B and Mo-Si-B alloys are currently the focus of materials research due to their excellent high temperature capabilities. To optimize the mechanical alloying (MA) process for these materials, we compare microstructures, morphology and particles size as well as hardness evolution during the milling process for the model alloys V-9Si-13B and Mo-9Si-8B. A variation of the rotational speed of the planetary ball mill and the type of grinding materials is therefore investigated. These modifications result in different impact energies during ball-powder-wall collisions, which are quantitatively described in this comparative study. Processing with tungsten carbide vials and balls provides slightly improved impact energies compared to vials and balls made of steel. However, contamination of the mechanically alloyed powders with flaked particles of tungsten carbide is unavoidable. In the case of using steel grinding materials, Fe contaminations are also detectable, which are solved in the V and Mo solid solution phases, respectively. Typical mechanisms that occur during the MA process such as fracturing and comminution are analyzed using the comminution rate K P . In both alloys, the welding processes are more pronounced compared to the fracturing processes.

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Section: Microstructure Of Compact Materialssupporting

confidence: 71%

Section: Microstructure Of Compact Materialsmentioning

confidence: 67%

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Krüger

Schmelzer

Helmecke

2016

Metals

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“…Similarly, kinetics of precipitation has also been examined by Sauza et al [22] and Vorontsov et al [23] in low supersaturated Co-8.8Al-7.3W at.% and Co-7Al-7W at.% alloys respectively, using scanning electron microscopy (SEM). The average size of γ' particles (R) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 4 was observed again to follow the LSW coarsening law (R 3 ~ t).…”

Section: Introductionmentioning

confidence: 99%

Kinetics pathway of precipitation in model Co-Al-W superalloy

et al. 2018

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Abstract:The early stages of precipitation of the γ ' phase in a model Co based superalloy (Co-9.1Al-7W (at.%)) have been investigated at 900 °C using electron microscopy and atom probe tomography. Nucleation, growth and coarsening stages have been studied with a focus on the temporal evolution of the precipitate composition in the light of recent theoretical developments on phase separation in multicomponent alloys. The experimental data have been confronted to the theories of nucleation and coarsening recently developed for such alloys, which are valid for non-ideal and non-dilute systems, and predict the temporal evolution of both the matrix and precipitate compositions. The rate constant for the mean size evolution of the particles, as derived from experiments, has been compared to the one predicted by the mentioned coarsening theory that accounts for a more accurate description of the thermodynamics of the phases, as compared with more classical approaches. From this comparison the γ/γ' interfacial energy was derived and found equal to ~48 mJ/m 2 . the exponents for the temporal evolution of average particles size, number of particles per unit volume were found identical to those for binary alloys during the coarsening regime, as expected, and the temporal evolutions of compositions in both γ and γ' phases were found to evolve as predicted by theory. Indeed, the W content in the particles, measured from atom probe tomography (APT) experiments, was found to significantly decrease with time and the observed evolution is remarkably well described by the theory and therefore is shown to originate from the competition between diffusion and capillarity.

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“…The smaller γ′ will dissolve, while the larger will continue to grow. The growth of the γ′ follows the LSW equation [32][33][34][35][36]:…”

Section: Microstructure Evolution Mechanism Of As-cast Alloy During Smentioning

confidence: 99%

Microstructure evolution of DD6 during different heat treatment conditions

Huang

Zhao

et al. 2019

Mater. Res. Express

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001] oriented DD6 alloy was prepared by directional solidification in this experiment. γ′ phase precipitation phase structure of different morphology and size was obtained by different high temperature ageing heat treatment processes. Through this experiment, the feasibility of improving high temperature performance by adjusting the heat treatment process to change the microstructure of the single crystal was explored. The as-cast DD6 is first subjected to standard heat treatment(SHT). The single crystal sample after the standard heat treatment was further kept at 900°C-1300°C for 10 min, 30 min and 1 h, finally air-cooled respectively. Heat treatment process of DD6 was simulated using Jmatpro software. The individual phase transition temperatures of the alloy were determined by DSC experiments. And the size and volume fraction of precipitated phase of the alloy were estimated using Image-Pro Plus software. It is concluded that the microstructure of the alloy obtained after holding at 1100°C for 30 min after standard heat treatment has the most uniform microstructure distribution.

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Coarsening behaviour and interfacial structure of γ′ precipitates in Co-Al-W based superalloys

Cited by 91 publications

References 39 publications

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Kinetics pathway of precipitation in model Co-Al-W superalloy

Microstructure evolution of DD6 during different heat treatment conditions

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