Second-Order Pyramidal Slip in Zinc Single Crystals

Abstract

Measurements of strain, dislocation mobility and dislocation density have been made in 99.999% zinc single crystals stressed at room temperature in compression along the hexagonal axis, [0001]. Slip bands on the〈1213〉{1212}, second-order pyramidal system were observed. Etch pit observations indicate that the average dislocation density increases linearly with strain. The velocity of edge dislocations in slip bands obeys the relation v = v_0(τ/τ_0)^n with v_0 = 1 in./sec, n = 8.7, τ_0 = 870 lb./in.^2, and τ 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 in determining the strain-rate sensitivity.

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