Dislocation Motion in Copper Single Crystals

Abstract

The characteristic motion of dislocations in copper single crystals of low dislocation density has been studied by etch pitting, especially near yield stress. Dislocations are presumed to be locked at each position in as-annealed crystals. The motion of dislocations due to the application of stress is composed of three processes: (1) unlocking from the as-annealed position, (2) moving at a high speed, e.g. 400 cm/sec at a stress of 22 g/mm ² , and (3) stopping at a certain final position depending on the stress level below yield stress. It is considered tentatively that the locking is due to discrete pinning by impurity atoms, and the main obstacles to the dislocation motion are thought to be other locked dislocations. From quantitative studies of each process a possible mechanism of yielding of copper crystals is suggested.