Journal ArticleDOI
Rafting in single crystal nickel-base superalloys - An overview
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TLDR
In this article, the effect of stress state on γ/γ′ rafting, kinetics and morphological evolution are discussed with the recent experimental results, and the nature and influence of rafting on creep properties including pre-rafted conditions are discussed.Abstract:
Currently nickel-base single crystal (SX) superalloys are considered for the manufacture of critical components such as turbine blades, vanes etc., for aircraft engines as well as land-based power generation applications. Microstructure and high temperature mechanical properties are the major factors controlling the performance of SX superalloys. Rafting is an important phenomenon in these alloys which occurs during high temperature creep. It is essential to understand the rafting mechanism, and its characteristics on high temperature properties before considering the advanced applications. In this review article, the thermodynamic driving force for rafting with and without stress is explained. The nature and influence of rafting on creep properties including pre-rafted conditions are discussed. In addition, the effect of stress state on γ/γ′ rafting, kinetics and morphological evolution are discussed with the recent experimental results.read more
Citations
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Damage accumulation during creep deformation of a single crystal superalloy at 1150 °C
TL;DR: In this article, microstructural degradation in the CMSX-4 single crystal superalloy during creep deformation at 1150°C and 100MPa is studied. And it is shown that the high strain rates and shear stresses associated with the rupture process are sufficient to cause realignment of the rafted γ′ structure with respect to the γ matrix.
Journal ArticleDOI
Coupling between Re segregation and γ/γ′ interfacial dislocations during high-temperature, low-stress creep of a nickel-based single-crystal superalloy
TL;DR: In this paper, a detailed characterization of interfacial dislocations in a DD6 superalloy after 12h at high temperature and low stress was carried out using transmission electron microscopy and high-angle annular dark field scanning transmission electron microscope techniques.
Journal ArticleDOI
Phase field study of precipitate rafting under a uniaxial stress
M. P. Gururajan,T.A. Abinandanan +1 more
TL;DR: In this article, a phase field model of an elastically inhomogeneous alloy was used to calculate elastic stress and strain fields for two-phase microstructures under a uniaxial applied stress.
Journal ArticleDOI
Observations of a〈0 1 0〉 dislocations during the high-temperature creep of Ni-based superalloy single crystals deformed along the [0 0 1] orientation
TL;DR: A NASAIR-100 superalloy single crystal was tested in tension creep at 1000°C at a stress of 148 MPa, for a time period of 20h and to a strain of 1.1% as mentioned in this paper.
Journal ArticleDOI
Atom probe informed simulations of dislocation-precipitate interactions reveal the importance of local interface curvature
Aruna Prakash,Julien Guénolé,J. Wang,Julian George Müller,Erdmann Spiecker,Michael J. Mills,Ivan Povstugar,Pyuck-Pa Choi,Dierk Raabe,Erik Bitzek +9 more
TL;DR: In this paper, the authors used atomistic simulation samples generated from atom probe tomography data of a single crystal superalloy to study the interactions of matrix dislocations with a γ ′ precipitate in molecular dynamics simulations.
References
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Journal ArticleDOI
Elstic energy changes accompanying gamma-prime rafting in nickel-base superalloys
Julius C. Chang,Samuel M. Allen +1 more
TL;DR: In this article, Eshelby's equivalent inclusion method is applied to the case of a single, inhomogeneous, ellipsoidal precipitate in an infinite matrix to study the morphological changes of the gamma-prime precipitates in nickel-base superalloys due to the influence of lattice constant misfit, elastic inhomogeneity and anisotropy, applied stress, and interfacial energy.
Journal ArticleDOI
Elastic stress in single crystal Ni-base superalloys and the driving force for their microstructural evolution under high temperature creep conditions
TL;DR: In this paper, a mechanism for "rafting" in Ni-base superalloys under high temperature creep conditions is discussed in terms of elastic strain energy, and the elastic deformation is analyzed by the finite element method and approximate analytical expressions are also deduced for it.
Journal ArticleDOI
On rafting in a single crystal nickel-base superalloy after high and low temperature creep
TL;DR: In this article, the conditions under which rafting occurred in other SX alloys and a brief summary of some important findings is given, such as: at low and intermediate temperature creep damage, it was not possible to see a change in the material with scanning electron microscopy, and at intermediate temperatures, 700-800 C, no microstructural changes were seen during the creep of SX-4 in tests which lasted less than a few thousand hours.
Journal ArticleDOI
Modelling of kinetics of directional coarsening in Ni-superalloys
Jiří Svoboda,P. Lukáš +1 more
TL;DR: In this paper, a model of kinetics of diffusion controlled directional coarsening (rafting) of γ-precipitates in Ni-superalloys has been developed based on the global energetic treatment using variational formulation of thermodynamics of irreversible processes.
Journal ArticleDOI
Mechanical behaviour and microstructural evolution in the single crystal superalloy SC16
TL;DR: In this article, the softening is accompanied by a morphological change in γ′ precipitates (rafting) and the observed microstructural instability leads to an increase in the spacing between the particles.