Cyclic Saturation Dislocation Structures of Multiple-Slip-Oriented Copper Single Crystals

The dislocation structures of [011] and [1¯11] multiple-slip-oriented Cu single crystals cyclically saturated at constant plastic strain amplitudes were investigated through transmission electron microscopy. The results obtained on [001] multiple-slip-oriented Cu single crystals were also included for summarization. Unlike the case for single-slip-oriented Cu single crystals, the crystallographic orientation has a strong effect on the saturation dislocation structure in these three multiple-slip-oriented crystals. For the [011] crystal, different dislocation patterns such as veins, PSB walls, labyrinths and PSB ladders were observed. The formation of PSB ladders is believed to be a major reason for the existence of a plateau region in the cyclic stress-strain (CSS) curve for the [011] crystal. The cyclic saturation dislocation structure of a [1¯11] crystal cycled at a low applied strain amplitude γpl of 2.0 × 10-4 was found to consist of irregular cells, which would develop into a more regular arrangement (e. g. PSB ladder-like) and the scale of which tends to decrease with increasing γpl. Finally, three kinds of representative micro-deformation mode were summarized and termed as labyrinth-mode (or [001]-mode), cell-mode (or [1¯11]-mode) and PSB ladder-mode (or [011]-mode). © 2001 Carl Hanser Verlag, München.