The effect of uniaxial stress on the periodic morphology of coherent gamma prime precipitates in nickel-base superalloy crystals

Tien, J. K.; Copley, S. M.

doi:10.1007/bf02662660

Cited by 262 publications

(64 citation statements)

References 6 publications

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“…This phenomenon, known as rafting, was first observed experimentally by Webster and Sullivan [186], Sullivan et al [183] and Tien and Copley [176]. A well-written short review of the subject is given in the paper by Nabarro et al [28].…”

Section: The Role Of Applied Stress; Raftingmentioning

confidence: 97%

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Fratzl¹,

Penrose²,

Joel³

1999

Journal of Statistical Physics

230

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Elastic interactions arising from a difference of lattice spacing between two coherent phases can have a strong influence on the phase separation (coarsening) of alloys. If the elastic moduli are different in the two phases, the elastic interactions may accelerate, slow down or even stop the phase separation process. If * Dedicated to John W. Cahn, on the occasion of his 70th birthday 1 the material is elastically anisotropic, the precipitates can be shaped like plates or needles instead of spheres and can form regular precipitate superlattices.Tensions or compressions applied externally to the specimen may have a strong effect on the shapes and arrangement of the precipitates. In this paper, we review the main theoretical approaches that have been used to model these effects and we relate them to experimental observations. The theoretical approaches considered are (i) 'macroscopic' models treating the two phases as elastic media separated by a sharp interface (ii) 'mesoscopic' models in which the concentration varies continuously across the interface (iii) 'microscopic' models which use the positions of individual atoms.

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Section: The Role Of Applied Stress; Raftingmentioning

confidence: 97%

Untitled

Fratzl¹,

Penrose²,

Joel³

1999

Journal of Statistical Physics

230

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“…An additional driving force for the formation of carbides is the reduction in strain energy associated with dislocations. Presumably, edge dislocations are favoured sites since they exhibit a higher net dilatation than Example of the effect of stress on γ /γ morphology in Udimet 700 [37]. The sample was stress annealed at 976 • C for 100 h at 157.5 MPa tension applied in the [001] direction (vertical direction).…”

Section: (I) Formation Of New Phasesmentioning

confidence: 99%

Microstructural aspects of fatigue in Ni-base superalloys

Antolovich

2015

Phil. Trans. R. Soc. A.

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Nickel-base superalloys are primarily used as components in jet engines and land-based turbines. While compositionally complex, they are microstructurally simple, consisting of small (50–1000 nm diameter), ordered, coherent Ni 3 (Al,Ti)-type L1 2 or Ni 3 Nb-type DO 22 precipitates (called γ ′ and γ ′′ , respectively) embedded in an FCC substitutional solid solution consisting primarily of Ni and other elements which confer desired properties depending upon the application. The grain size may vary from as small as 2 μm for powder metallurgy alloys used in discs to single crystals the actual size of the component for turbine blades. The fatigue behaviour depends upon the microstructure, deformation mode, environment and cycle time. In many cases, it can be controlled or modified through small changes in composition which may dramatically change the mechanism of damage accumulation and the fatigue life. In this paper, the fundamental microstructural, compositional, environmental and deformation mode factors which affect fatigue behaviour are critically reviewed. Connections are made across a range of studies to provide more insight. Modern approaches are pointed out in which the wealth of available microstructural, deformation and damage information is used for computerized life prediction. The paper ends with a discussion of the very important and highly practical subject of thermo-mechanical fatigue (TMF). It is shown that physics-based modelling leads to significantly improved life prediction. Suggestions are made for moving forward on the critical subject of TMF life prediction in notched components.

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“…During prolonged exposure at high temperature the coagulation of γ phase occurs. The evolution of the γ phase in SC nickel-base superalloys was the subject of many studies [4][5][6][7][8][9][10][11][12]. Especially, the directional coagulation under the influence of external stress, generally known as rafting, was studied in detail in many superalloys [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Analytical Electron Microscopy Studies of the CMSX-4 Single Crystal Superalloy Subjected to High Temperature Annealing

et al. 2017

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The aim of the present work is to investigate the development of the γ/γ microstructure and the changes in chemical composition of γ and γ phases during high temperature annealing of CMSX-4 superalloy at a temperature of 1100• C in the time range from 500 to 2500 h. The studies were performed by means of scanning electron microscopy and the modern scanning-transmission electron microscopy with Super-X EDS system of four SDD detectors. Results of scanning electron microscopy and scanning-transmission electron microscopy analyses have shown that the microstructure of CMSX-4 superalloy is unstable during ageing at high temperature and the coalescence of cuboidal γ precipitates was observed. Energy dispersive X-ray microanalysis revealed the distribution of particular alloying elements in the γ and γ phases and the differences in their concentration in the function of the annealing time.

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The effect of uniaxial stress on the periodic morphology of coherent gamma prime precipitates in nickel-base superalloy crystals

Cited by 262 publications

References 6 publications

Untitled

Untitled

Microstructural aspects of fatigue in Ni-base superalloys

Analytical Electron Microscopy Studies of the CMSX-4 Single Crystal Superalloy Subjected to High Temperature Annealing

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