An investigation of diffusion-mediated cyclic coarsening and reversal coarsening in an advanced Ni-based superalloy

Yiqiang  Chen; R.  Prasath babu; Thomas J.A.  Slater; M. Bai; Robert Mitchell; Octav  Ciuca; Michael Preuss; Sarah J.  Haigh

doi:10.1016/j.actamat.2016.02.067

An investigation of diffusion-mediated cyclic coarsening and reversal coarsening in an advanced Ni-based superalloy

Yiqiang Chen, R. Prasath babu, Thomas J.A. Slater, M. Bai, Robert Mitchell, Octav Ciuca, Michael Preuss, Sarah J. Haigh

Research output: Contribution to journal › Article › peer-review

74 Citations (Scopus)

70 Downloads (Pure)

Abstract

The anomalous cyclic coarsening behaviour of γ′ precipitates after ageing at 1073 K has been investigated for the low misfit commercial powder metallurgy (PM) Ni-based superalloy RR1000. Using scanning transmission electron microscope (STEM) imaging combined with absorption-corrected energy-dispersive X-ray (EDX) spectroscopy, the elemental segregation as a function of coarsening behaviour has been experimentally observed for secondary γ′ precipitates. Elemental EDX spectrum imaging has revealed nanoscale enrichment of Co and Cr and a depletion of Al and Ti within the γ matrix close to the γ-γʹ interface. Our experimental results, coupled with complementary modelling and synchrotron X-ray diffraction analysis, demonstrate the importance of elastic strain energy resulting from local compositional variations for influencing precipitate morphology. In particular, elemental inhomogeneities, as a result of complex diffusive interactions within both matrix and precipitates, play a crucial role in determining the rate of coarsening. Our findings provide important new evidence for understanding the microstructural evolution observed for advanced superalloys when they are exposed to different heat treatment regimes.

Original language	English
Pages (from-to)	295-305
Number of pages	11
Journal	Acta Materialia
Volume	110
Early online date	24 Mar 2016
DOIs	https://doi.org/10.1016/j.actamat.2016.02.067
Publication status	Published - 15 May 2016
Externally published	Yes

Bibliographical note

Keywords

Ni based superalloys
coarsening
precipitates
Scanning transmission electron microscopy
elemental mapping
energy dispersive X-ray spectroscopy

Access to Document

10.1016/j.actamat.2016.02.067Licence: CC BY

PublishedFinal published version, 3.34 MBLicence: CC BY

Cite this

@article{35430c66616a4b0babaeb101e71461ac,

title = "An investigation of diffusion-mediated cyclic coarsening and reversal coarsening in an advanced Ni-based superalloy",

abstract = "The anomalous cyclic coarsening behaviour of γ′ precipitates after ageing at 1073 K has been investigated for the low misfit commercial powder metallurgy (PM) Ni-based superalloy RR1000. Using scanning transmission electron microscope (STEM) imaging combined with absorption-corrected energy-dispersive X-ray (EDX) spectroscopy, the elemental segregation as a function of coarsening behaviour has been experimentally observed for secondary γ′ precipitates. Elemental EDX spectrum imaging has revealed nanoscale enrichment of Co and Cr and a depletion of Al and Ti within the γ matrix close to the γ-γʹ interface. Our experimental results, coupled with complementary modelling and synchrotron X-ray diffraction analysis, demonstrate the importance of elastic strain energy resulting from local compositional variations for influencing precipitate morphology. In particular, elemental inhomogeneities, as a result of complex diffusive interactions within both matrix and precipitates, play a crucial role in determining the rate of coarsening. Our findings provide important new evidence for understanding the microstructural evolution observed for advanced superalloys when they are exposed to different heat treatment regimes.",

keywords = "Ni based superalloys, coarsening, precipitates, Scanning transmission electron microscopy, elemental mapping, energy dispersive X-ray spectroscopy",

author = "Yiqiang Chen and {Prasath babu}, R. and Slater, {Thomas J.A.} and M. Bai and Robert Mitchell and Octav Ciuca and Michael Preuss and Haigh, {Sarah J.}",

note = "{\textcopyright} 2016 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).",

year = "2016",

month = may,

day = "15",

doi = "10.1016/j.actamat.2016.02.067",

language = "English",

volume = "110",

pages = "295--305",

journal = "Acta Materialia",

issn = "1359-6454",

publisher = "Elsevier",

}

TY - JOUR

T1 - An investigation of diffusion-mediated cyclic coarsening and reversal coarsening in an advanced Ni-based superalloy

AU - Chen, Yiqiang

AU - Prasath babu, R.

AU - Slater, Thomas J.A.

AU - Bai, M.

AU - Mitchell, Robert

AU - Ciuca, Octav

AU - Preuss, Michael

AU - Haigh, Sarah J.

PY - 2016/5/15

Y1 - 2016/5/15

N2 - The anomalous cyclic coarsening behaviour of γ′ precipitates after ageing at 1073 K has been investigated for the low misfit commercial powder metallurgy (PM) Ni-based superalloy RR1000. Using scanning transmission electron microscope (STEM) imaging combined with absorption-corrected energy-dispersive X-ray (EDX) spectroscopy, the elemental segregation as a function of coarsening behaviour has been experimentally observed for secondary γ′ precipitates. Elemental EDX spectrum imaging has revealed nanoscale enrichment of Co and Cr and a depletion of Al and Ti within the γ matrix close to the γ-γʹ interface. Our experimental results, coupled with complementary modelling and synchrotron X-ray diffraction analysis, demonstrate the importance of elastic strain energy resulting from local compositional variations for influencing precipitate morphology. In particular, elemental inhomogeneities, as a result of complex diffusive interactions within both matrix and precipitates, play a crucial role in determining the rate of coarsening. Our findings provide important new evidence for understanding the microstructural evolution observed for advanced superalloys when they are exposed to different heat treatment regimes.

AB - The anomalous cyclic coarsening behaviour of γ′ precipitates after ageing at 1073 K has been investigated for the low misfit commercial powder metallurgy (PM) Ni-based superalloy RR1000. Using scanning transmission electron microscope (STEM) imaging combined with absorption-corrected energy-dispersive X-ray (EDX) spectroscopy, the elemental segregation as a function of coarsening behaviour has been experimentally observed for secondary γ′ precipitates. Elemental EDX spectrum imaging has revealed nanoscale enrichment of Co and Cr and a depletion of Al and Ti within the γ matrix close to the γ-γʹ interface. Our experimental results, coupled with complementary modelling and synchrotron X-ray diffraction analysis, demonstrate the importance of elastic strain energy resulting from local compositional variations for influencing precipitate morphology. In particular, elemental inhomogeneities, as a result of complex diffusive interactions within both matrix and precipitates, play a crucial role in determining the rate of coarsening. Our findings provide important new evidence for understanding the microstructural evolution observed for advanced superalloys when they are exposed to different heat treatment regimes.

KW - Ni based superalloys

KW - coarsening

KW - precipitates

KW - Scanning transmission electron microscopy

KW - elemental mapping

KW - energy dispersive X-ray spectroscopy

UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84961629090&partnerID=MN8TOARS

U2 - 10.1016/j.actamat.2016.02.067

DO - 10.1016/j.actamat.2016.02.067

M3 - Article

SN - 1359-6454

VL - 110

SP - 295

EP - 305

JO - Acta Materialia

JF - Acta Materialia

ER -

An investigation of diffusion-mediated cyclic coarsening and reversal coarsening in an advanced Ni-based superalloy

Abstract

Bibliographical note

Keywords

Access to Document

Other files and links

Fingerprint

Cite this