Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1582096 | Materials Science and Engineering: A | 2008 | 12 Pages |
Abstract
The addition of 3 wt.% ruthenium (Ru) was found to improve both the intermediate temperature/intermediate stress and the high temperature/low stress creep behaviours of two high refractory content single crystal Ni-base superalloys. Creep rupture tests, creep activation energy measurements and microstructural analysis indicate that Ru serves a dual role; it enhances microstructural stability by suppressing the precipitation of deleterious topologically close-packed (TCP) phases and it increases the level of solid solution strengthening of the γ phase. Its effectiveness as a TCP suppressant increases with temperature whereas its potency as a strengthening element decreases with temperature. Ru reduces the stacking fault energy of the γ phase and this is thought to have a significant contribution towards its strengthening benefit at intermediate temperatures. The reduction in γⲠvolume fraction upon the addition of Ru, which is central to its effectiveness as a stabilising element, appears to be the principal cause of its diminishing strengthening contribution at elevated temperatures.
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Authors
R.A. Hobbs, L. Zhang, C.M.F. Rae, S. Tin,