Stress-Dependence of Activation Volume of Dislocation Glide by Dispersed Local Obstacles

Abstract

Thermal activation analysis permits the interaction potential between gliding dislocations and obstacles to be determined, if certain assumptions are made. The stress-dependence of the activation volume of four given simple potentials is summarized and compared with measurements for Zn and Mg. It is pointed out that the differences in the stress-dependence of the activation volume for different interaction potentials are much greater than those of the temperature-dependence of flow stress. The Gibbs free energy of activation of obstacle intersection in Zn was determined as ∆G ₀ = 0·67 ± 0·06 eV.