Journal ArticleDOI
Morphology of y’ and y” precipitates and thermal stability of inconel 718 type alloys
R. Cozar,André Pineau +1 more
- Vol. 4, Iss: 1, pp 47-59
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In this article, the precipitation microstructure varies rapidly with aging temperature and composition, and the influence of composition and aging temperature on the conditions that bring about this compact morphology has been investigated.Abstract:
The precipitation of the γ’ (Ll2) and γ" (DO22) phases has been studied in four alloys Fe-Ni-Cr-Ti-Al-Nb containing a higher Ti + Al/Nb ratio than that of the INCONEL 718 alloy. For these alloys, the precipitation microstructure varies rapidly with aging temperature and composition. Bct γ"particles have always been found to precipitate on γ’ phase. Moreover, by aging three alloys above a critical temperature, a “compact ntorphology” has been observed: cube-shaped γ’ particles coated on their six faces with a shell of γ" precipitate. This microstructure has proved to be very stable on prolonged aging. A thermal stability better than that encountered in nominal INCONEL 718 alloy can thus be achieved. The influence of composition and aging temperature on the conditions that bring about this “compact morphology” has been investigated. A minimal Ti + Al/Nb ratio between 0.9 and 1 has been determined, allowing the “compact morphology” to be obtained.read more
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Formation mechanisms of coprecipitates in Inconel 718 Superalloys
TL;DR: In this paper , the authors used phase field simulations to analyze the individual and combined effects of concentration and coherency stress fields associated with a growing γ′ precipitate at different sizes on heterogeneous nucleation of γ″ on the surfaces of the particle and the coprecipitate configurations formed.
Journal ArticleDOI
Structure Formation and Mechanical Characteristics of Dispersion-Hardening Alloy Based on Ni–Cr–Nb–Mo System
TL;DR: In this article, the presence of intermetallic phases of three modifications coherently associated with the matrix in the material after dispersion hardening was established using scanning electron microscopy (SEM), X-ray diffractometric analysis, and transmission electron microscope (TEM).
Journal ArticleDOI
Role of precipitates-decorated Σ3 twin boundaries on hydrogen-induced crack initiation and propagation in Ni-based superalloy 718
TL;DR: The role of ∑3 twin boundaries (∑3s) on hydrogen embrittlement behavior of Ni-based superalloy 718 was investigated by uniaxial tensile tests as mentioned in this paper .
Journal ArticleDOI
Automatic Feature Extraction from Micrographs of Forged Superalloys
TL;DR: In this article, image-processing-based feature extraction was used to improve the accuracy of grain size estimation for forged superalloys, which can be applied to a wide range of ASTM grain size numbers from G3 to G12.
References
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Journal ArticleDOI
The Determination of the Elastic Field of an Ellipsoidal Inclusion, and Related Problems
TL;DR: In this paper, it is shown that to answer several questions of physical or engineering interest, it is necessary to know only the relatively simple elastic field inside the ellipsoid.
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Déformations de cohérence d'un précipité quadratique
TL;DR: In this paper, exact expressions for the elastic field due to a perfectly coherent precipitate having the form of a rectangular parallelepiped, the material being supposed elastically homogeneous and isotropic.
Journal ArticleDOI
The microstructure of 706, a new Fe−Ni-base superalloy
TL;DR: In this article, the phase relationships of Alloy 706 alloy were investigated and it was shown that on the basis of chemistry and micro-structural response, Alloy 606 alloy can be considered to be intermediate to the well-known alloys, 718 and 901.
Journal ArticleDOI
Heterogeneous precipitation of metastable γ′-ni3ti in a nickelbase alloy
TL;DR: In this article, the effect of prior deformation on the precipitation of L12 γ′-Ni3Ti in nickel-base Alloy 901 was investigated by thin foil microscopy.
Journal ArticleDOI
Fine Faults and Crystal Structures of Precipitates in Fe-Mo and Fe-W Alloys
Kōhei Yagisawa,Hiroshi Fujita +1 more
TL;DR: In this paper, the crystal structure and two-dimensional faults of the precipitates in Fe-Mo alloys were investigated using electron microscopic method, and the faults were found on {00.1}hex, {10.0}hex and {100}hex planes.