skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Lattice parameter misfit evolution during creep of a cobalt-based superalloy single crystal with cuboidal and rafted gamma-prime microstructures

Abstract

A [h00] oriented Co-based superalloy single crystal was crept under tension at 940 °C=100 MPa, resulting in a P-type raft morphology with extensive particle coalescence along the [h00] loading direction. However, particle coalescence was also observed in two perpendicular directions on the (h00) plane, normal to the loading axis. Tensile creep experiments were performed with in-situ neutron diffraction at 800 °C=500 MPa on this initially rafted $$\gamma$$ microstructure, and for comparison at (i) 900 °C=260 MPa, and at (ii) 750 °C=875 MPa, both with initially cuboidal $$\gamma$$ microstructures. The alloy was shown to exhibit a positive lattice parameter misfit, and during the first hour of creep at 900 °C=260 MPa, the lattice parameter evolution indicated changes in phase composition associated with $$\gamma$$ dissolution as the alloy achieved phase equilibrium at 900 °C. For all three in-situ creep measurements, there was a significant divergence of the $$\gamma$$ and g lattice parameters as creep proceeded. The lattice parameter misfit values between the precipitates and the matrix approached their unconstrained values during creep, and were notably large compared to those of Ni-based superalloys. This is indicative of a loss of coherency at the precipitate/matrix interfaces. Such a loss of coherency at the precipitate/matrix interfaces will likely degrade certain mechanical properties such as fatigue resistance, as has been shown for the Ni-based superalloys.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [3];  [4];  [5];  [5]
  1. Northwestern Univ., Evanston, IL (United States); Univ. of Cambridge (United Kingdom)
  2. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Cambridge (United Kingdom)
  5. Northwestern Univ., Evanston, IL (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE; European Union (EU); National Science Foundation (NSF)
OSTI Identifier:
1559749
Alternate Identifier(s):
OSTI ID: 1550183
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 136; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Coakley, James, Lass, Eric A., Ma, Dong, Frost, Matthew, Stone, Howard J., Seidman, David N., and Dunand, David C. Lattice parameter misfit evolution during creep of a cobalt-based superalloy single crystal with cuboidal and rafted gamma-prime microstructures. United States: N. p., 2017. Web. doi:10.1016/j.actamat.2017.06.025.
Coakley, James, Lass, Eric A., Ma, Dong, Frost, Matthew, Stone, Howard J., Seidman, David N., & Dunand, David C. Lattice parameter misfit evolution during creep of a cobalt-based superalloy single crystal with cuboidal and rafted gamma-prime microstructures. United States. doi:10.1016/j.actamat.2017.06.025.
Coakley, James, Lass, Eric A., Ma, Dong, Frost, Matthew, Stone, Howard J., Seidman, David N., and Dunand, David C. Tue . "Lattice parameter misfit evolution during creep of a cobalt-based superalloy single crystal with cuboidal and rafted gamma-prime microstructures". United States. doi:10.1016/j.actamat.2017.06.025. https://www.osti.gov/servlets/purl/1559749.
@article{osti_1559749,
title = {Lattice parameter misfit evolution during creep of a cobalt-based superalloy single crystal with cuboidal and rafted gamma-prime microstructures},
author = {Coakley, James and Lass, Eric A. and Ma, Dong and Frost, Matthew and Stone, Howard J. and Seidman, David N. and Dunand, David C.},
abstractNote = {A [h00] oriented Co-based superalloy single crystal was crept under tension at 940 °C=100 MPa, resulting in a P-type raft morphology with extensive particle coalescence along the [h00] loading direction. However, particle coalescence was also observed in two perpendicular directions on the (h00) plane, normal to the loading axis. Tensile creep experiments were performed with in-situ neutron diffraction at 800 °C=500 MPa on this initially rafted $\gamma$ microstructure, and for comparison at (i) 900 °C=260 MPa, and at (ii) 750 °C=875 MPa, both with initially cuboidal $\gamma$ microstructures. The alloy was shown to exhibit a positive lattice parameter misfit, and during the first hour of creep at 900 °C=260 MPa, the lattice parameter evolution indicated changes in phase composition associated with $\gamma$ dissolution as the alloy achieved phase equilibrium at 900 °C. For all three in-situ creep measurements, there was a significant divergence of the $\gamma$ and g lattice parameters as creep proceeded. The lattice parameter misfit values between the precipitates and the matrix approached their unconstrained values during creep, and were notably large compared to those of Ni-based superalloys. This is indicative of a loss of coherency at the precipitate/matrix interfaces. Such a loss of coherency at the precipitate/matrix interfaces will likely degrade certain mechanical properties such as fatigue resistance, as has been shown for the Ni-based superalloys.},
doi = {10.1016/j.actamat.2017.06.025},
journal = {Acta Materialia},
number = C,
volume = 136,
place = {United States},
year = {2017},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 11 works
Citation information provided by
Web of Science

Save / Share: