Observation of Dislocation Multiplication and Texture Formation during High-Temperature Compressive Deformation in Pure Copper

We studied the fundamental phenomena of flow stress variations with deformation temperature and plastic strain during high-temperature deformation of copper. Oxygen-free copper specimens were compressed at room temperature, 573, 673, and 773 K. Dislocation density and texture evolution were evaluated by in-situ neutron diffraction measurements during the compressive deformation. The higher the deformation temperature, the lower the dislocation density during deformation. This was induced by dynamic recovery and recrystallization, which are more likely to occur at higher temperatures. The flow stresses estimated from the Bailey-Hirsch equation based on dislocation densities determined from neutron diffraction measurements reproduced the experimental temperature dependence of the flow stress, including stress oscillations. The dislocation strengthening factor, which determines flow stress from dislocation density, decreased at higher temperatures, suggesting that the frequency of forest interaction between dislocations decreased with increasing deformation temperatures. This may be due to the recovery caused by the dislocation climb. {110} texture developed with the compressive deformation. The higher the deformation temperature, the weaker the texture evolved. Texture evolution in high-temperature deformation proceeded similarly to that in room-temperature deformation until stress oscillations occurred. On the other hand, once stress oscillations began, the texture evolution was retarded.