This title appears in the Scientific Report :
2018
Please use the identifier:
http://dx.doi.org/10.1007/s11661-018-4705-1 in citations.
Thermophysical and Mechanical Properties of Advanced Single Crystalline Co-base Superalloys
Thermophysical and Mechanical Properties of Advanced Single Crystalline Co-base Superalloys
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 th...
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Personal Name(s): | Volz, N. (Corresponding author) |
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Zenk, C. H. / Cherukuri, R. / Kalfhaus, T. / Weiser, M. / Makineni, S. K. / Betzing, C. / Lenz, M. / Gault, B. / Fries, S. G. / Schreuer, J. / Vaßen, R. / Virtanen, S. / Raabe, D. / Spiecker, E. / Neumeier, S. / Göken, M. | |
Contributing Institute: |
Werkstoffsynthese und Herstellungsverfahren; IEK-1 |
Published in: | Metallurgical and materials transactions / A, 49A (2018) 9, S. 4099-4109 |
Imprint: |
Boston
Springer
2018
|
DOI: |
10.1007/s11661-018-4705-1 |
Document Type: |
Journal Article |
Research Program: |
Methods and Concepts for Material Development |
Publikationsportal JuSER |
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 |