Effect of “deformational” and thermal annealing on the stability of dislocation structure in Zn crystals

Abstract

The stability of the pyramidal dislocation forest of the {11 2 2} 〈11 2 3〉 system in Zn single crystals, under repeated straining on the (0001) [2 1 1 0] slip system with intermediate annealing, has been studied. The stability of the hardened state is shown to depend greatly on the annealing temperature and the plastic deformation processes in the basic slip system. Thus, we may consider two types of annealing: deformational and thermal, whose joint influence on the crystal always has a greater effect than that of ordinary thermal annealing alone. The conclusion is drawn that the decrease of the forest dislocation density and of the yield stress are bound to a strong elastic interaction between the basal and pyramidal dislocations for forest densities above a critical value (>4 × 10 5 cm −2).