Epsilon and Eta Phases Precipitated in an Fe-38Ni-13Co-4.7Nb1.5Ti-0.4Si Superalloy.

Kusabiraki, Kiyoshi; Amada, Eiji; Ôoka, Takayuki; Saji, Shigeoki

doi:10.2355/isijinternational.37.80

Cited by 22 publications

(30 citation statements)

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“…The presence of copious amounts of e phase in STOA condition was observed to reduce the yield strength and hardness compared to c9 strengthened commercially STA condition. 5. The e phase exhibits ordered APBs, confirming the earlier research by Guo et al …”

Section: Discussionsupporting

confidence: 90%

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Overaged metallography of alloy 909, a low coefficient of expansion superalloy

Balachander

Vishwakarma

Richards

2012

Materials Science and Technology

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The microstructure of alloy 909, a low coefficient of thermal expansion Fe-Co-Ni superalloy was examined in the solution treated and over aged condition, following a previous communication by the authors on the solution treated and commercially aged alloys. In the commercially aged alloy, only the Laves and the γ‚ phases were observed. With some indication, however, of alignment of the γ‚ phase along crystallograpic directions in the austenitic matrix. This alignment of the γ‚ phase has been previously reported as a precursor to the growth of the ϵ phase from the γ‚ phase. Analysis by TEM showed that the platelet phase was hexagonal (NiFeCo)2(TiNb) with some variations in the stoichiometry about 2:1 ratio. Tensile and hardness testing indicated that the presence of the platelet shaped ϵ phase in the solution treated and overaged condition was not as effective in the strengthening of the alloys as the spherical γ‚ in the commercially aged and solution treated condition. In addition to the presence of ϵ phase, blocky A2B Laves phase was abundant, which prevents excessive grain growth up to ∼1040°C

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Section: Discussionsupporting

confidence: 90%

“…The e phase with stacking order (abab) has been shown by Kusibiraki et al 5 to form from the metastable c9 phase having stacking order (abcabc). At temperatures in excess of y750uC, the phase can also precipitate directly out into the austenite matrix.…”

Section: Resultsmentioning

confidence: 97%

Overaged metallography of alloy 909, a low coefficient of expansion superalloy

Balachander

Vishwakarma

Richards

2012

Materials Science and Technology

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“…The alloy containing 3wt% Ti and 0·5wt% Al is strengthened by fine precipitation of the γ (Ni 3 AlTi) phase in the matrix by aging after solution heat treatment, also including the solid solution hardening of Mo and grain boundary hardening of B. The alloy possesses heat resisting properties up to about 700 • C. The low cost and excellent working properties resulted in it being widely applied in gas turbine as high temperature attaching parts and spring (Kusabiraki et al 1996(Kusabiraki et al , 1997(Kusabiraki et al , 1998. Since these components withstand high alternating stresses and creep loads, uniform microstructure with fine grains must be obtained by controlling forging processes.…”

Section: Introductionmentioning

confidence: 99%

Processing maps for Fe–24Ni–11Cr–3Ti–1Mo superalloy

et al. 2011

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Hot deformation characteristics of a Fe-base superalloy were studied at various temperatures from 1000-1200 • C under strain rates from 0·001-1 s −1 using hot compression tests. Processing maps for hot working are developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate and interpreted by a dynamic materials model. Hot deformation equation was given to characterize the dependence of peak stress on deformation temperature and strain rate. Hot deformation apparent activation energy of the Fe24Ni-11Cr-1Mo-3Ti superalloy was determined to be about 499 kJ/mol. The processing maps obtained in a strain range of 0·1-0·7 were essentially similar, indicating that strain has no significant influence on it. The processing maps exhibited a clear domain with a maximum of about 40-48% at about 1150 • C and 0·001 s −1 .

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“…Annealing twins are the significant features in the microstructure of recrystallized materials having low to medium stacking fault energy. 12) Existence of twins in both the small and large grains indicates that twins are generated during both the recrystallization and grain growth stages, respectively. 13) Additionally, some particles such as Ti(N,C) which are formed during solidification are observed in solution annealed material.…”

Section: Phases In the Solution Annealed Alloymentioning

confidence: 99%

Effect of ^|^eta; Phase on Mechanical Properties of the Iron-based Superalloy Using Shear Punch Testing

et al. 2013

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In this paper, the shear deformation behavior of A286 Iron-based superalloy was studied with an emphasis on the influence of η phase on shear strength. The η (Ni3Ti) phase precipitates at high temperature heat treatment or during services at the expense of gamma prime phase. According to the microstructural features, no evidences of η phase were found at 650 and 720°C. η phase precipitated at 780 and 840°C and the amount of it increased with an increase the time and temperature. Because of using the alloy as fasteners, investigation of shear properties and the influence of η phase on it are indispensable. The shear strength of the alloy with different volume fractions of η was examined. It was found that, with an increase of η volume fraction, the ultimate shear strength decreases. The shear punch fracture surfaces were also examined by the scanning electron microscopy. The fracture surfaces of sheared samples indicated that low and high volume fraction of η phase result in interior cracks and grain boundary decohesion, respectively. In fact, the fracture of weak grain boundary films (η phase) produces this kind of decohesive cracking.KEY WORDS: A286 superalloy; η phase; high temperature phase transformation; shear punch test; fracture surface.

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Epsilon and Eta Phases Precipitated in an Fe-38Ni-13Co-4.7Nb1.5Ti-0.4Si Superalloy.

Abstract: An Fe-38Ni-1 3C0-4.7Nb-1 .5Ti-0.5Si alloy is a controlled low thermal expansion superalloy with a good resistance to SAGBO (

Cited by 22 publications

References 1 publication

Overaged metallography of alloy 909, a low coefficient of expansion superalloy

Overaged metallography of alloy 909, a low coefficient of expansion superalloy

Processing maps for Fe–24Ni–11Cr–3Ti–1Mo superalloy

Effect of ^|^eta; Phase on Mechanical Properties of the Iron-based Superalloy Using Shear Punch Testing

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