Electron Microscopic Observations of Dislocations in Thin Foils of Iron Stretched in Tension

Abstract

The arrangement of dislocations in the thin foils of pure iron deformed in tension was examined by transmission electron microscopy. The mean dislocation density increases from 106/cm2 or less to the order of 1011/cm2 with greater deformation and then becomes approximately constant up to about 30% strain. Dislocations observed do not distribute uniformly over a grain. Most of the dislocations lie in an irregular sub-boundary network which separates regions comparatively free of dislocations. Such a cell structure becomes more pronunced with increasing elongation. The misorientation between cells has a tendency to increase with greater deformation. Annihilation of dislocations, formation and movement of sub-boundary are observed in the thin section during the strong irradiation of electron beam.