Friction stress σ0and relationship between initial and secondary creep rates in precipitation-hardened nickel-base alloy

Abstract

AbstractFollowing recent work on the friction stress σ0 approach to secondary creep behaviour it is shown for Nimonic 90 that a further parameter, [σ0]in, can be determined which allows the technique to be extended to the initial creep stage. The [σ0]in term is the intercept resulting from extrapolation of the secondary σ0 data to zero applied stress. Details on the extrapolation are presented and the results used to relate initial and secondary creep rates. The significance of [σ0]in is then discussed particularly in relation to theγ ′ precipitate in Nimonic 90. Finally, it is shown that existing models for dislocation climb at precipitate particles can be adopted to account for the magnitude of [σ0]in.