Modelling the tertiary creep behaviour of an oxide dispersion strengthened nickel based alloy

A modified model of constrained cavity growth controlled by the power law creep of adjacent grains has been presented and exemplified with heats of different grain aspect ratio N of the nickel-base superalloy PM 1000. Tensile creep tests at a constant true stress of sigma approximate to 200 MPa have been performed in air at 1123 K. The course of the creep curve in the tertiary stage is calculated by incrementally increasing creep time and subsequent calculation of the damage parameter. The proposed approach accounts for the observed increase of the creep rate (epsilon) over dot in the tertiary stage and correctly reflects the influence of the grain aspect ratio N on (epsilon) over dot. (C) 1997 Elsevier Science B.V.