Direct Observations of the Arrangement and Motion of Dislocations in Aluminium

Abstract

Electron optical experiments on Al foils have revealed individual dislocations in the interior of the metal. The arrangement and movement of individual dislocations have been observed. Most of the dislocations occur in the boundaries of a substructure, the diameter of the subrains being of the order of 1 μ or more. Tilt-boundaries, networks and disloca- tion nodes have been resolved. The results apply to aluminium recovered at 350°C after heavy deformation by beating; the dislocation density is 10¹⁰/cm².

The dislocations can be seen to move along traces of (111) slip planes; the motion of the dislocations can be either rapid or slow and jerky. Cross-slip by the screw dislocation mechanism has been observed frequently.

†Communicated by the Authors.

Acknowledgments

Our thanks are due to Professor N. F. Mott, F.R.S., Dr. W.H. Taylor, and Dr. V. E. Cosslett, for their interest, encouragement and helpful discussions. The micrographs were taken on a Siemens and Halske Elmiskop I electron microscope, purchased through a generous benefaction from the Nuffield Foundation. We are also grateful to Messrs George Whiley and Co. for supplying the beaten foils.

Acknowledgments for grants are due to the Ministry of Supply (P. B. H), to the Agricultural Research Council (R. W. H.), and to the Department of Scientific and Industrial Research (M. J. W.).

Notes

†Communicated by the Authors.