Dislocation behaviour and the formation of persistent slip bands in fatigued copper single crystals observed by high-voltage electron microscopy

Abstract Dislocation behaviour in fatigued copper single crystals with [123] and [111] fatigue axes has been investigated dynamically by in situ experiments with a high-voltage electron microscope to clarify the origin of persistent slip bands (PSBs) and how the ladder structure is formed. From observations of the fatigued [123] specimen, the following points have been clarified concerning the development of the PSBs and the ladder structure. (1) Only primary dislocations are activated in the ladder structure whose dislocation walls are perpendicular to the primary Burgers vector. (2) The dislocation walls of the ladder structure are easily cut by the glide of dislocations on the cross-slip plane. (3) The ladder structure disappears more quickly than the vein structure when the fatigued specimens are heated inside the electron microscope. (4) The vein structures observed from the direction perpendicular to the cross-slip plane tend to arrange themselves parallel to the traces of the conjugate and critical...