Second Order Pyramidal Slip in Zinc

Measurements of strain, dislocation density, and dislocation velocity have been made in 99.999% Zn stressed in compression along the hexagonal axis, [0001]. Slip bands on the second order pyramid,〈1213〉{1212}, system were observed. The average dislocation density increases linearly with strain. The velocity of edge dislocations in slip bands obeys the relation v = (Γ/ Γ_0)^n with v in in. / sec, n = 8.7, Γ_0 = 870 lb/in.^2, and Γ the resolved shear stress in lb/in^2. These observations together with measurements of the strain rate sensitivity of the flow stress show that the stress dependence of the density of moving dislocations is more important than the stress dependence of the dislocation velocity as they affect the strain rate.