Dislocation drag processes

Experiments showing the influence of electron drag on mobile dislocations are presented. These show that dislocations overcome barriers sequentially during low temperature deformation. Also, the influence of viscosity on rate processes is demonstrated through creep studies of lead alloys in the normal state and the superconducting state. Finally, experiments are described which provide real time measurements of instantaneous dislocation velocities during ordinary tensile deformation. All of these results are tied together through the overriding principle of treating dislocations as underdamped oscillators.