Forest Dislocations in Silver Single Crystals

The distributions of primary and forest dislocations in silver single crystals deformed in single glide by varying amounts into stage I and stage II of the work-hardening curve have been studied by the etch-pitting technique. The distributions of the primary dislocations found are in agreement with previous etch-pitting studies on f.c.c. metals. The distributions of forest dislocations are markedly different from those of the primary dislocations in that dense ‘strings’ of dislocations lying roughly perpendicular to the primary Burgers vector and parallel to the primary glide plane were found throughout stage I and into stage II. The number of strings and the dislocation density within them increase with strain while the density of the forest dislocations outside of the strings remains approximately equal to that of the virgin, as-grown crystal until the onset of stage II. The etch-pitted strings are believed to correspond to the primary dislocation bundles seen in transmission electron microscopy.