Single crystals up to 20cm in length and containing as little as 120ppm of interstitial oxygen were grown from the melt. The deformation modes operating at various crystal orientations and the effect of purity, temperature, orientation and strain rate on the work-hardening parameters were investigated. In prismatic slip, three stages of work hardening similar to those in face-centered cubic crystals were identified. Stages I and II were associated with single and conjugate slip, respectively, while dynamic recovery in stage-III occurred due to cross-slip from the prism to the basal plane. From the temperature and strain-rate sensitivity of the stress at the onset of cross-slip, the stacking-fault energy of Zr on the prism planes was calculated to be 56mJ/m2.

Plastic Deformation of Zirconium Single Crystals. A.Akhtar, A.Teghtsoonian: Acta Metallurgica, 1971, 19[7], 655-63