The growth of γ′ precipitates in nickel-base superalloys

Ricks, R. A.; Porter, Angus; Ecob, R. C.

doi:10.1016/0001-6160(83)90062-7

Cited by 335 publications

(130 citation statements)

References 11 publications

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“…On further aging to 100 hours, octodendritic precipitates alongside smaller, cuboidal precipitates were observed, characteristic of the morphological instabilities associated with precipitate splitting. [16,17] Following aging for 200 hours, only octodendritic precipitates were observed throughout the sample. After 1000 hours, the secondary γ′ appeared finer and more spherical than those observed during shorter duration exposures.…”

Section: Resultsmentioning

confidence: 99%

“…In alloys with moderate to high lattice misfits, morphological changes of this type are commonly associated with the magnitude of the lattice misfit, with a progression from spheres to cuboids and finally to octodendrites, in order to minimize the elastic strain energy of the matrix as the precipitates coarsen. [16,17] However, in this alloy, the lattice misfit is low, and therefore the precipitates would be expected to remain spheroidal throughout aging.…”

Section: A Precipitate Morphologymentioning

confidence: 99%

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Gamma Prime Precipitate Evolution During Aging of a Model Nickel-Based Superalloy

Goodfellow

Galindo-Nava

Christofidou

et al. 2017

Metall Mater Trans A

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The microstructural stability of nickel-based superalloys is critical for maintaining alloy performance during service in gas turbine engines. In this study, the precipitate evolution in a model polycrystalline Ni-based superalloy during aging to 1000 hours has been studied via transmission electron microscopy, atom probe tomography, and neutron diffraction. Variations in phase composition and precipitate morphology, size, and volume fraction were observed during aging, while the constrained lattice misfit remained constant at approximately zero. The experimental composition of the γ matrix phase was consistent with thermodynamic equilibrium predictions, while significant differences were identified between the experimental and predicted results from the γ′ phase. These results have implications for the evolution of mechanical properties in service and their prediction using modeling methods.

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Section: Resultsmentioning

confidence: 99%

Section: A Precipitate Morphologymentioning

confidence: 99%

Gamma Prime Precipitate Evolution During Aging of a Model Nickel-Based Superalloy

Goodfellow

Galindo-Nava

Christofidou

et al. 2017

Metall Mater Trans A

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“…In previous experimental works, we studied the y ' precipitation during continuous cooling from the y domain [16,19]. Microstructural observation of samples quenched from different temperatures during the precipitation process (between 1250°C and 1150°C) showed that a growing precipitate encounters successive shape changes.…”

mentioning

confidence: 99%

“…Nevertheless, the typical distorded morphology illustrated in Fig. 10 is actually very often observed during the y ' precipitation process [8,19,20]. This disagreement between modelling and experiment is explained by the fact that the model does not take the kinetics aspect of the process into account, while the star morphology is clearly a transient stage of the shape evolution during precipitate growth.…”

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confidence: 99%

Internal Mismatch Stresses in Nickel-Based Superalloys : A Finite Element Approach

1996

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Abstract. A three-dimensional finite element (F.E.) model is used to estimate the mismatch stresses at a microscopic scale in y -y ' single-crystal nickel-based snpedloys. F.E. calculations point out the specificity of stress/strain distributions in these alloys, in particular the fact that internal stresses concentrate in the connected y matrix. The analysis of stress/strain fields and elastic energy evolution as a function of precipitate morphology and volume fraction allows to explain some atypical precipitate shape changes such as "splitting" during precipitation treatments or "raftening" during high temperature creep tests.

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“…This is consistent with previously published work on the coarsening of ', which is reflected in the coarsening constants incorporated in the model and listed in Table 2. Assuming that the normal r 3 LSW coarsening law applies [18,29], r for the tertiary particles will be 10 2 and 10 4 faster than for the secondary and primary particles respectively. It would be expected that the tertiary ' would eventually dissolve and reprecipitate on the secondary particles.…”

Section: Application To Turbine Disc Alloysmentioning

confidence: 99%

A Generic Microstructure-Explicit Model of Creep in Nickel-Base Superalloys

Basoalto¹,

Sondhi²,

Dyson³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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Past approaches to modelling the creep behaviour of engineering alloys have been either totally empirical or, while having functional forms consistent with current understanding of deformation and fracture mechanisms, have been calibrated by comparison with an available creep database. They have not specifically included quantitative measures of the microstructural features that are thought to impart creep resistance to the alloys. The present paper reviews and extends a microstructure-specific model of creep in particle-strengthened alloys in which the model parameters are directly related to measurable characteristics of the microstructure of nickel-base superalloys. The model accounts for three previously identified changes in microstructure that occur during the creep of superalloys: (i) coarsening of the precipitate; (ii) the progressive increase in mobile dislocation density with accumulated creep strain; and (iii) the development of grain boundary cavities. The relative dominance of each will be demonstrated using a set of commercial alloys with specific alloy microstructures. It is emphasised that the model-generated curves are true predictions using input microstructural characteristics and are not empirically fitted to the creep data.

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The growth of γ′ precipitates in nickel-base superalloys

Cited by 335 publications

References 11 publications

Gamma Prime Precipitate Evolution During Aging of a Model Nickel-Based Superalloy

Gamma Prime Precipitate Evolution During Aging of a Model Nickel-Based Superalloy

Internal Mismatch Stresses in Nickel-Based Superalloys : A Finite Element Approach

A Generic Microstructure-Explicit Model of Creep in Nickel-Base Superalloys

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