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A new polycrystalline Co-Ni superalloy
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Knop, M., Mulvey, P., Ismail, F., Radecka, A., Rahman, K. M., Lindley, T. C., Shollock, Barbara A., Hardy, M. C., Moody, M. P., Martin, T. L., Bagot, P. A. J. and Dye, D. (2014) A new polycrystalline Co-Ni superalloy. JOM . doi:10.1007/s11837-014-1175-9 ISSN 1047-4838.
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Official URL: http://dx.doi.org/10.1007/s11837-014-1175-9
Abstract
In 2006, a new-ordered L12 phase, Co3(Al,W), was discovered that can form coherently in a face-centered cubic (fcc) A1 Co matrix. Since then, a community has developed that is attempting to take these alloys forward into practical applications in gas turbines. A new candidate polycrystalline Co-Ni γ/γ′ superalloy, V208C, is presented that has the nominal composition 36Co-35Ni-15Cr-10Al-3W-1Ta (at.%). The alloy was produced by conventional powder metallurgy superalloy methods. After forging, a γ′ fraction of ~56% and a secondary γ′ size of 88 nm were obtained, with a grain size of 2.5 μm. The solvus temperature was 1000°C. The density was found to be 8.52 g cm−3, which is similar to existing Ni alloys with this level of γ′. The alloy showed the flow stress anomaly and a yield strength of 920 MPa at room temperature and 820 MPa at 800°C, similar to that of Mar-M247. These values are significantly higher than those found for either conventional solution and carbide-strengthened Co alloys or the γ/γ′ Co superalloys presented in the literature thus far. The oxidation resistance, with a mass gain of 0.08 mg cm−2 in 100 h at 800°C, is also comparable with that of existing high-temperature Ni superalloys. These results suggest that Co-based and Co-Ni superalloys may hold some promise for the future in gas turbine applications.
Item Type: | Journal Article | ||||
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Divisions: | Faculty of Science, Engineering and Medicine > Engineering > WMG (Formerly the Warwick Manufacturing Group) | ||||
Journal or Publication Title: | JOM | ||||
Publisher: | Springer New York LLC | ||||
ISSN: | 1047-4838 | ||||
Official Date: | 17 October 2014 | ||||
Dates: |
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DOI: | 10.1007/s11837-014-1175-9 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
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