Influence of strain amplitude on the internal friction of cold-worked and electron-irradiated copper

The effect is studied of strain amplitude and the variation of pinner number on the internal friction of cold-worked copper. At very low temperatures a large decrease in the internal friction is observed versus strain amplitude for values below 10−6 which is interpreted by the motion of preexisting geometrical kinks along dislocations. The strain amplitude does not strongly influence the Bordoni peak, but largely effects the Hasiguti peak P1 and the background damping near room temperature. It is shown that irradiation induced point defects limit the movement of geometrical kinks at low temperature, but enhance the internal friction in the Hasiguti peaks temperature range.