Effective stress in steady-state creep in alpha Cu–Zn solid solutions

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Abstract
Effective stress in steady-state creep in alpha Cu–10% Zn and Cu–30% Zn alloys in a temperature interval 723 to 973 K was measured using the strain transient dip test technique. The measured effective stress was found to be higher at higher zinc concentration than at any given applied stress. The apparent internal stress [sgrave] = [sgrave] – [sgrave]∗ is related rather to dislocation distribution than to dislocation density as compared in both alloys investigated. The apparent activation energy obtained, where is the steady-state creep rate, represents a purely phenomenological quantity which cannot be compared with the activation energy of dislocation glide. The same applies to the activation area determined on the assumption that the moving dislocation density is proportional to the total dislocation density. It is concluded that high-temperature creep in the alloys investigated is controlled by recovery due to dislocation climb and annihilation, and that the recovery is not driven by the apparent internal stress. The internal stress driving recovery in creep is close to the applied stress.