Abstract
Creep tests of a CoNiCrAlY bond coat alloy were conducted in the temperature range from 1073 K to 1473 K. The alloy was prepared from a powder with a nominal chemical composition of 34.2% Co, 28.6% Ni, 21.2% Cr, 15.6% Al, 0.4% Y (atomic percent is given throughout) by consolidating it under a stress of 60 MPa and annealing it at 1473 K. The final composition of the alloy is 36.3% Co, 29.6% Ni, 21.0% Cr, 12.8% Al and 0.3% Y. The stress exponent n decreases with the increasing temperature from 3.9 at 1073 K to approximately 1 at 1473 K. Consequently, the activation energy of creep is stress dependent and ranges from 512 kJ/mol to 224 kJ/mol with increasing stress. Combined creep and constant strain rate data can be described by the Garofalo (sinh) equation. A comparison of the results with available creep data of free-standing bond coats is presented. Creep resistance of the present alloy clearly overwhelms the resistance of bond coat alloys previously summarized by Wood.
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