MODELING THE TERTIARY CREEP-BEHAVIOR 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 h eats of different grain aspect ratio N of the nickel-base superalloy P M 1000. Tensile creep tests at a constant true stress of sigma approxi mate to 200 MPa have been performed in air at 1123 K. The course of th e creep curve in the tertiary stage is calculated by incrementally inc reasing 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) 1 997 Elsevier Science B.V.