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
The effect of orientation and sense of applied uniaxial stress on the morphology of coherent gamma prime precipitates in stress annealed nickel-base superalloy crystals
J. K. Tien,Stephen M. Copley +1 more
TL;DR: In this article, a general thermodynamic analysis of the effect of stress annealing on precipitate morphology is presented that takes into account free energy changes due to changes in bulk precipitation strain, effective modulus, coherency strain energy, and the total interphase boundary area.
Journal ArticleDOI
γ′-cutting as rate-controlling recovery process during high-temperature and low-stress creep of superalloy single crystals
TL;DR: In this paper, the pairwise cutting of the γ′-phase after high-temperature and low-stress shear creep deformation of superalloy single crystals was investigated using weak-beam and high-resolution transmission electron microscopy.
Journal ArticleDOI
Effect of initial gamma prime size on the elevated temperature creep properties of single crystal nickel base superalloys
TL;DR: In this article, the influence of initial size and shape on the high temperature creep properties of two single crystal nickel-base superalloys was investigated, and the two alloys were chosen to represent different magnitudes of γ-γ′ lattice mismatch.
Journal ArticleDOI
On the formation of 〈010〉-dislocations in the γ′-phase of superalloy single crystals during high temperature low stress creep
Gunther Eggeler,A. Dlouhy +1 more
TL;DR: In this article, the cutting of γ-particles by dislocations during shear creep deformation of CMSX 6 superalloy single crystals loaded on the macroscopic crystallographic shear system at T = 1025°C and τ = 85 MPa was analyzed using transmission electron microscopy (TEM).
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Elevated temperature creep-rupture behavior of the single crystal nickel-base superalloy NASAIR 100
Michael V. Nathal,L. J. Ebert +1 more
TL;DR: In this article, the creep and rupture behavior of oriented single crystals of the nickel-base superalloy NASAIR 100 was investigated at temperatures of 925 and 1000 °C. The creep rate exponents for this alloy were between seven and eight, and the modulus-corrected activation energy for creep was approximately 350 kjoule/mole.