Abstract
A polycrystalline hot working ingot metallurgy processing route for γ/γ′ Co-Al-W superalloys has been developed. Based on Co-7Al-7W (at%), substitutions of Mo, V, Ti, Ta, Ni, Si, Fe and Cr were examined. The γ′ solvus was found to follow the same trends as those exhibited by alloys with higher γ′ fractions considered by other investigators. Excessive Cr additions were found to lead to discontinuous coarsening and eventually, the loss of the γ′ phase from the microstructures observed. Ni additions were examined, with some success, and found to restore the γ′ phase and raise the solvus temperature. It was found that the addition of 13 at.% Cr improved the oxidation resistance at 800 C by over 40 times.
| Original language | English |
|---|---|
| Pages (from-to) | 44-53 |
| Number of pages | 10 |
| Journal | Intermetallics |
| Volume | 48 |
| Early online date | 20 Nov 2013 |
| DOIs | |
| Publication status | Published - 31 May 2014 |
Funding
The authors would like to acknowledge the financial support provided by Rolls-Royce plc . and EPSRC (UK) under the Dorothy Hodgkin Postgraduate Awards scheme (H-Y.Y) and by grant EP/H004882/1 (D.D., V.A.V.). Useful conversations with Mark Hardy at Rolls-Royce plc. are also acknowledged. We would also like to thank Richard Sweeney, Mahmoud Ardakani, Matthias Knop and Nicholas G Jones for their assistance, as well as Kevin Roberts at the University of Cambridge.
Keywords
- aluminides
- oxidation
- phase diagrams
- precipitates
- miscellaneous
- polycrystalline hot working ingot metallurgy
