Characterization of dislocation microstructures in cyclically deformed [001] copper single crystals using high voltage scanning transmission electron microscopy

Abstract

Low-cycle fatigue tests of copper single crystals with the [001] stress axis were performed at room temperature under constant plastic shear strain amplitudes between γpl=3.5×10−4 and 1.0×10−2. Characteristic dislocation structures, which are highly dependent on a given plastic strain amplitude, were observed by high voltage scanning transmission electron microscopy. A vein-like dislocation structure, having a parallelepiped shape with two longitudinal (100) and (001) sides, was periodically formed along the [010] direction at around γpl=1.0×10−3. Labyrinth structure with the (100) and (001) dislocation walls was then gradually developed with increasing plastic strain amplitude.