Journal Article

FZJ-2018-03299

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Thermophysical and Mechanical Properties of Advanced Single Crystalline Co-base Superalloys

Volz, N. (Corresponding author) ; Zenk, C. H. ; Cherukuri, R. ; Kalfhaus, T.FZJ* ; Weiser, M. ; Makineni, S. K. ; Betzing, C. ; Lenz, M. ; Gault, B. ; Fries, S. G. ; Schreuer, J. ; Vaßen, R.FZJ* ; Virtanen, S. ; Raabe, D. ; Spiecker, E. ; Neumeier, S. ; Göken, M.

2018
Springer Boston

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Please use a persistent id in citations: doi:10.1007/s11661-018-4705-1

Abstract: A set of advanced single crystalline γ′ strengthened Co-base superalloys with at least nine alloying elements (Co, Ni, Al, W, Ti, Ta, Cr, Si, Hf, Re) has been developed and investigated. The objective was to generate multinary Co-base superalloys with significantly improved properties compared to the original Co-Al-W-based alloys. All alloys show the typical γ/γ′ two-phase microstructure. A γ′ solvus temperature up to 1174 °C and γ′ volume fractions between 40 and 60 pct at 1050 °C could be achieved, which is significantly higher compared to most other Co-Al-W-based superalloys. However, higher contents of Ti, Ta, and the addition of Re decrease the long-term stability. Atom probe tomography revealed that Re does not partition to the γ phase as strongly as in Ni-base superalloys. Compression creep properties were investigated at 1050 °C and 125 MPa in 〈001〉 direction. The creep resistance is close to that of first generation Ni-base superalloys. The creep mechanisms of the Re-containing alloy was further investigated and it was found that the deformation is located preferentially in the γ channels although some precipitates are sheared during early stages of creep. The addition of Re did not improve the mechanical properties and is therefore not considered as a crucial element in the design of future Co-base superalloys for high temperature applications. Thermodynamic calculations describe well how the alloying elements influence the transformation temperatures although there is still an offset in the actual values. Furthermore, a full set of elastic constants of one of the multinary alloys is presented, showing increased elastic stiffness leading to a higher Young’s modulus for the investigated alloy, compared to conventional Ni-base superalloys. The oxidation resistance is significantly improved compared to the ternary Co-Al-W compound. A complete thermal barrier coating system was applied successfully

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)

Research Program(s):

1. 113 - Methods and Concepts for Material Development (POF3-113) (POF3-113)

Appears in the scientific report 2018

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Database coverage:
Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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