Stress dependence of the strain rate of Al-11 wt.% Zn at elevated temperature

Abstract

During creep of AlZn 11 at 523 K the activation area Δa and the athermal component of flow stress σ i have been measured by the stress change and the stress relaxation techniques. The values of Δa and σ i are correlated to the dislocation structure of AlZn 11 and are used to calculate the activation work ΔW. In the stress range from 10 to 31 MN/m 2 the steady state values of ΔW increase from about 2 to 8 kT corresponding to about 7 and 23% of the activation energy for self diffusion. The stress dependence of the creep rate ge during steady state creep and the strain dependence of ge during transient creep are consistently described by the relation ge ∝ ρ i exp ( ΔW/ kT) where ρ i is the density of dislocations in the subgrain interior.