Characterization of dislocation structures in copper single crystals using electron channelling contrast technique in SEM

The dislocation structures induced by low-plastic-strain-amplitude cyclic deformation of [(1) over bar 11] multiple-slip-oriented Cu single crystals were investigated using electron channelling contrast (ECC) technique in scanning electron microscopy (SEM). At a low plastic strain amplitude gamma(pl) of 8.8 x 10(-5), the saturated dislocation structure is mainly composed of labyrinth-like vein structure (or irregular labyrinths), and the cyclic hardening behavior at such a low gamma(pl) is interpreted as being the result of dislocation multiplication by a Frank-Read mechanism. As gamma(pl) increases to 4.0 x 10(-4), the unsaturated dislocation structure exhibits two kinds of distinctive configurations, i.e., dislocation walls and misoriented cells. Interestingly, these misoriented dislocation cells are strictly aligned along the primary slip plane (111), constituting a unique persistent slip band (PSB) structure. Here, these cells are thus called PSB cells. In addition, there is a locally distinctive region comprising some cells having a recrystallization-like feature in the whole structure of PSB cells. The formation of the structure of PSB cells is discussed. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim