Comparison of a Brownian motion rate theory with dislocation damping data for lead

A Brownian motion rate theory of dislocation motion taking account of viscous and inertial effects is applied to internal friction measurements. Results for superconducting Pb are used to determine the distribution of the breakaway stress of dislocations. The parameters found by analysis of the internal friction data, including the electronic damping coefficient, are those needed to account as well for the enhanced plasticity as for the anomalous flow stress temperature dependence of dilute alloys.