Dislocation structures in copper single crystals fatigued at low amplitudes

Abstract

Single crystals cycled over a wide range of strains, below and up to those of the plateau in the cyclic stress-strain curve, have been prepared by ultrasonic fatigue. The dislocation structures of these specimens have been examined by transmission electron microscopy (TEM) and details of the structures, including the dimensions and varieties of the structures and the identities of the dislocations, have been documented. Special attention has been given to the occurrence of secondary dislocations and their role in the dislocation mechanisms, such as the transformation of loop patches into persistent slip bands.