The influence of strain rate on the mechanical properties and dislocation substructure in deformed copper single crystals

Abstract The mechanical properties, dislocation configurations and densities have been investigated in single crystals of copper deformed in the strain-rate range 10 −4 to 10 4 sec −1 . It was found that the flow stress of copper exhibits two regions of strain-rate sensitivity. Below strain rates of 10 3 sec −1 the flow stress was relatively insensitive to strain rate but above 10 3 sec −1 the flow stress is a sensitive linear function of the strain rate. However, the dislocation density and configurations versus strain were found to be almost independent of strain rate throughout the range 10 −4 to 10 4 sec −1 . There was a straight line relationship between the flow stress and the square root of the dislocation density at all strain rates. However, at a strain rate of 6·5 X 10 3 sec −1 there is a positive intercept τ 0 on the stress axis at zero dislocation density. The term τ 0 can be related to the damping process retarding dislocation motion.