Theoretical descriptions of climb controlled steady state creep at high and intermediate temperatures

Abstract

Steady state creep via diffusion controlled dislocation climb is examined with particular reference to the role of dislocation core self diffusion. Several models for steady state creep controlled by dislocation climb lead to a creep equation of the form epsi ̇ = A Gb kT[DL + β( σ G)2Dc]( σ G)3, where β varies from 1 to 10 and A is about 10. Two new models which account for the effect of dislocation curvature on the climb motion of the dislocation are introduced in this paper. They also lead to the above creep equation. These models and the resulting creep equation provide a basis for an effective diffusivity to be used in cases where both lattice and core self diffusion are involved. However, a review of the available creep data for pure metals at high and intermediate temperatures shows that the effective diffusivity concept is not fully consistent with experiment. Discrepancies between the above creep equation and existing data suggest that current theoretical descriptions are still incomplete. © 1979.