THE PLASTIC DEFORMATION OF THIN COPPER SINGLE CRYSTALS: II. AN ELECTRON MICROSCOPE STUDY OF THE SURFACE STRUCTURE

Abstract

A comparison is made between the slip-line structure of two copper single crystals, where the glide path length of edge dislocations is 1.44 mm and 0.066 mm, respectively. No significant difference is found. This leads to the conclusion that dislocations that escape at the surface of a crystal are generated very close to it.Stress–strain experiments on thin layers of crystal from the surface and from the center of previously deformed crystals confirm that slip lines are not representative of the bulk deformation. They also show that a flow-stress gradient exists between the surface and the center of the crystal. It is argued that the existence of such a gradient can be used to explain the dependence of the extent of stage I on the glide path length of edge dislocations.