Dislocation Damping at High Strain Rates in Aluminum and Aluminum-Copper Alloy

Impact shear tests have been used to study the dependence of shear stress with shear-strain rate at strain rates ranging from 0.5×104 to 2.2×104 sec−1 in pure Al, prestrained Al, and Al-2 at. % Cu alloy. Within this strain-rate range a linear relationship was found between shear-stress and shear-strain rates, indicating the presence of a viscous drag on dislocations. The dependence on temperature of this viscous damping was investigated between 10° and 293°K. The results are discussed in terms of theories of phonon viscosity and phonon scattering, and of electron viscosity at low temperatures.