Quaternary alloying effects and the prospects for a new generation of Co-base superalloys

Hui Yu Yan, Vassili A. Vorontsov, James Coakley, Nicholas G. Jones, Howard J. Stone, David Dye

Research output: Contribution to conferenceProceeding

18 Citations (Scopus)

Abstract

Polycrystalline Co-Al-W alloys with quaternary alloying substitutions have been studied to investigate whether this alloy system might be attractive as an alternative to Ni-base superalloys in high temperature applications. A process route for the alloys was developed and an initial aging heat treatment established. The initial findings indicate that the addition of Ti, Ta and Ni increases the solvus temperature, whereas the addition of Mo lowers it slightly. The addition of Ti, Ta and Ni to the base alloy increased the γ′ precipitate size, whereas the addition of Mo had a negligible effect. Diffraction measurements were performed using both X-ray and neutron scattering. Positive lattice misfit values were obtained at both room and elevated temperatures; moreover, the lattice misfit increased with temperature. The thermal expansion coefficient of the γ phase was similar to reference data for Co, whereas the γ′ phase had a greater thermal expansion coefficient than the γ phase. Finally, cyclic oxidation experiments have been carried out in air at 800 °C. The CoO scales grown were not protective, and the alloys suffered from spallation during cooling.

Original languageEnglish
Pages705-714
Number of pages10
DOIs
Publication statusPublished - 1 Dec 2012
Event12th International Symposium on Superalloys, Superalloys 2012 - Seven Springs, PA, United States
Duration: 9 Sep 201213 Sep 2012

Conference

Conference12th International Symposium on Superalloys, Superalloys 2012
CountryUnited States
CitySeven Springs, PA
Period9/09/1213/09/12

Fingerprint

heat resistant alloys
Superalloys
Alloying
alloying
Thermal expansion
thermal expansion
High temperature applications
spallation
coefficients
Neutron scattering
X ray scattering
Temperature
temperature
Precipitates
precipitates
neutron scattering
heat treatment
Substitution reactions
Aging of materials
Diffraction

Keywords

  • Co3(Al,W)
  • cobalt
  • lattice misfit
  • oxidation
  • solvus
  • superalloys

Cite this

Yan, H. Y., Vorontsov, V. A., Coakley, J., Jones, N. G., Stone, H. J., & Dye, D. (2012). Quaternary alloying effects and the prospects for a new generation of Co-base superalloys. 705-714. 12th International Symposium on Superalloys, Superalloys 2012, Seven Springs, PA, United States. https://doi.org/10.1002/9781118516430.ch78
Yan, Hui Yu ; Vorontsov, Vassili A. ; Coakley, James ; Jones, Nicholas G. ; Stone, Howard J. ; Dye, David. / Quaternary alloying effects and the prospects for a new generation of Co-base superalloys. 12th International Symposium on Superalloys, Superalloys 2012, Seven Springs, PA, United States.10 p.
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Yan, HY, Vorontsov, VA, Coakley, J, Jones, NG, Stone, HJ & Dye, D 2012, 'Quaternary alloying effects and the prospects for a new generation of Co-base superalloys' 12th International Symposium on Superalloys, Superalloys 2012, Seven Springs, PA, United States, 9/09/12 - 13/09/12, pp. 705-714. https://doi.org/10.1002/9781118516430.ch78

Quaternary alloying effects and the prospects for a new generation of Co-base superalloys. / Yan, Hui Yu; Vorontsov, Vassili A.; Coakley, James; Jones, Nicholas G.; Stone, Howard J.; Dye, David.

2012. 705-714 12th International Symposium on Superalloys, Superalloys 2012, Seven Springs, PA, United States.

Research output: Contribution to conferenceProceeding

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AU - Vorontsov, Vassili A.

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AU - Stone, Howard J.

AU - Dye, David

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N2 - Polycrystalline Co-Al-W alloys with quaternary alloying substitutions have been studied to investigate whether this alloy system might be attractive as an alternative to Ni-base superalloys in high temperature applications. A process route for the alloys was developed and an initial aging heat treatment established. The initial findings indicate that the addition of Ti, Ta and Ni increases the solvus temperature, whereas the addition of Mo lowers it slightly. The addition of Ti, Ta and Ni to the base alloy increased the γ′ precipitate size, whereas the addition of Mo had a negligible effect. Diffraction measurements were performed using both X-ray and neutron scattering. Positive lattice misfit values were obtained at both room and elevated temperatures; moreover, the lattice misfit increased with temperature. The thermal expansion coefficient of the γ phase was similar to reference data for Co, whereas the γ′ phase had a greater thermal expansion coefficient than the γ phase. Finally, cyclic oxidation experiments have been carried out in air at 800 °C. The CoO scales grown were not protective, and the alloys suffered from spallation during cooling.

AB - Polycrystalline Co-Al-W alloys with quaternary alloying substitutions have been studied to investigate whether this alloy system might be attractive as an alternative to Ni-base superalloys in high temperature applications. A process route for the alloys was developed and an initial aging heat treatment established. The initial findings indicate that the addition of Ti, Ta and Ni increases the solvus temperature, whereas the addition of Mo lowers it slightly. The addition of Ti, Ta and Ni to the base alloy increased the γ′ precipitate size, whereas the addition of Mo had a negligible effect. Diffraction measurements were performed using both X-ray and neutron scattering. Positive lattice misfit values were obtained at both room and elevated temperatures; moreover, the lattice misfit increased with temperature. The thermal expansion coefficient of the γ phase was similar to reference data for Co, whereas the γ′ phase had a greater thermal expansion coefficient than the γ phase. Finally, cyclic oxidation experiments have been carried out in air at 800 °C. The CoO scales grown were not protective, and the alloys suffered from spallation during cooling.

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Yan HY, Vorontsov VA, Coakley J, Jones NG, Stone HJ, Dye D. Quaternary alloying effects and the prospects for a new generation of Co-base superalloys. 2012. 12th International Symposium on Superalloys, Superalloys 2012, Seven Springs, PA, United States. https://doi.org/10.1002/9781118516430.ch78