Evolution of dislocation structure during inverse creep of a nickel aluminide: Ni–23.5 Al–0.5 Hf–0.2B (at. %)

Abstract

A well-annealed polycrystalline nickel aluminide of composition Ni–23.5Al–0.5 Hf–0.2B (at. %) shows inverse creep behavior at 1033 K and 250 MPa. The minimum creep rate does not correspond to a steady-state creep condition. The increase in the creep rate with strain and time is accompanied by an increase in the volume fraction of dislocation-containing regions. The inverse transient can be eliminated by prestraining at room temperature. It is absent in the diffusional creep regime.