Temperature dependence of the flow stress and the strain rate sensitivity at the transition from the Peierls mechanism to pinning by localized obstacles

Barriers of very different character such as localized obstacles and the ex tended Peierls- Nabarro relief may control the dislocation motion in crysta ls in different stress and temperature ranges. The great difference in the microscopic parameters characterizing these two mechanisms, e.g., in the ac tivation volumes, manifests itself even on the macroscopic scale as a stron g change of the plastic properties in a rather narrow transition range of t he temperature. A theory describing the temperature dependence of the flow stress and the strain rate sensitivity near the transition has: been develo ped and compared with experimental data on the plastic deformation of cubic ZrO2 single crystals in a soft orientation.