Ferritic Fe–Al–Ni–Cr alloys with coherent precipitates for high-temperature applications

Stallybrass, C. O.; Sauthoff, Gerhard

doi:10.1016/j.msea.2004.01.108

Cited by 86 publications

(65 citation statements)

References 10 publications

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“…For atom probe analysis, rods of this material were sharpened by electropolishing to have a radius of curvature of less than 100 nm at the apex. Three phases in the microstructure were identified consistent with prior work [1]. A primary Fe-rich phase (A2), a secondary NiAl phase (B2), and a third Fe-rich precipitate.…”

supporting

confidence: 77%

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A Correlative Study of an Iron-Base Superalloy Using Transmission Electron Microscopy and Atom Probe Tomography

Larson¹,

Prosa²,

Kostrna³

et al. 2006

Microsc Microanal

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Many heat resistant ferritic steels have superior thermal expansion and conductivity properties compared to Ni-based alloys but are somewhat limited in their applications above ~600 o C by their mechanical properties. Efforts are being made to use precipitation strengthening to improve these properties and thus the efficiency of such alloys [1]. One such effort uses coherent (Ni,Fe)Al precipitates in a ferritic matrix, Fig. 1, and has shown good initial results. Transmission electron microscopy (TEM) has been used to understand globally the precipitate microstructure as it evolves with heat treatment. In order to understand the mechanisms by which such precipitation occurs, it is important to know how the composition variations in the structure on the scale of the precipitates evolve with heat treatment. Atom probe tomography (APT) [2] excels at such atomicscale characterization and is a strong complement to the imaging capabilities of TEM. The local electrode atom probe (LEAP) [3] has been used to characterize the nanoscale microstructure in this alloy in order to determine the chemistry of the third phase (yellow arrow) precipitated inside the (Ni,Fe)Al B2 phase, which is shown as the darkly-imaging phase in Fig. 1b. The Fe-18.1at.% Ni-22.9at.% Al-9.5at.% Cr alloy was produced by vacuum induction melting followed by solution annealing at 1200°C with air cooling. For atom probe analysis, rods of this material were sharpened by electropolishing to have a radius of curvature of less than 100 nm at the apex. Three phases in the microstructure were identified consistent with prior work [1]. A primary Fe-rich phase (A2), a secondary NiAl phase (B2), and a third Fe-rich precipitate. Precipitates of the primary phase within the secondary phase were not seen to form within ~15 nm of large scale primary regions, i.e., there is a denuded zone or precipitate free zone near the primary phase A2 phase. Fig. 2 shows a LEAP analysis with a volume of (80x80x500) nm made up of 110 million atoms. On the right side of Fig. 2, two composition profiles are shown. The top one is across a narrow B2 region between two A2 regions showing the ~50/50 composition of the NiAl phase in this region. The lower profile reveals that the very small (~5nm) precipitates (yellow arrow in Fig. 1) inside the NiAl phase appear to be secondary Fe-rich phase. Through this correlative microscopy effort with TEM and APT, a greater understanding of the precipitation sequence and evolution of the microstructure is obtained.

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supporting

confidence: 77%

“…Efforts are being made to use precipitation strengthening to improve these properties and thus the efficiency of such alloys [1]. One such effort uses coherent (Ni,Fe)Al precipitates in a ferritic matrix, Fig.…”

mentioning

confidence: 99%

A Correlative Study of an Iron-Base Superalloy Using Transmission Electron Microscopy and Atom Probe Tomography

Larson¹,

Prosa²,

Kostrna³

et al. 2006

Microsc Microanal

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“…Thus, prior to aging, this sample also experienced fine carbide precipitation, which increased the strength regardless of the lower amount of carbide. This is because the carbide morphology plays an important role in terms of the strengthening effect, as stated previously by Stallybrass et al (2004). Meanwhile, at temperatures of 900 o C and 975 o C, carbide dissolution was hardly observed in the microstructure.…”

Section: Hardnesssupporting

confidence: 55%

“…The reason for this behavior is that a large amount of carbide had been dissolved as the heating temperature reached 1125 o C, then the aging process promoted the carbide to precipitate but in a controlled atmosphere, which results in finely dispersed particles of carbide precipitates in the matrix. Stallybrass et al (2004) explained that this form of carbide can give a better strengthening effect than coarser carbide. In addition, the increment in grain size from 1050 o C to 1125 o C was only around 4μm, which did not have a significant effect in reducing its strength.…”

Section: Hardnessmentioning

confidence: 99%

Effect of Aging Treatment on the Microstructures and Hardness of Fe-Ni-Cr Superalloy

Jumaidin¹,

Hamzah²,

Selamat³

et al. 2013

Int J Automot Mech Eng

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“…Fig. 3 illustrates the clear correlation observed between APT and TEM for a Ferritic iron-base superalloy [9]. Good correlation is also observed between APT and secondary ion mass spectrometry.…”

mentioning

confidence: 62%

Compositional Imaging at the Atomic Scale with Atom Probe Tomography

Kelly¹,

Bunton²,

Thompson³

et al. 2006

Microsc Microanal

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Ferritic Fe–Al–Ni–Cr alloys with coherent precipitates for high-temperature applications

Cited by 86 publications

References 10 publications

A Correlative Study of an Iron-Base Superalloy Using Transmission Electron Microscopy and Atom Probe Tomography

A Correlative Study of an Iron-Base Superalloy Using Transmission Electron Microscopy and Atom Probe Tomography

Effect of Aging Treatment on the Microstructures and Hardness of Fe-Ni-Cr Superalloy

Compositional Imaging at the Atomic Scale with Atom Probe Tomography

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