Dislocation Mobility in Aluminum

Dislocation velocities in aluminum were measured, using the etch-pit technique of Gilman and Johnston, as a function of stress in the temperature region between liquid-helium temperature and room temperature. The dislocation-damping constant B was calculated at various temperatures from the linear portion of the velocity-vs-stress curve. The value of B decreases with decreasing temperature in the region from room temperature to 30°K. This result agrees with theoretical predictions of the dislocation damping produced by phonon-dislocation interactions. Below 30°K the damping constant B increases with decreasing temperature. This latter result disagrees with the accepted theoretical predictions of dislocation damping produced by electron-dislocation interactions.