A weak-beam electron microscopy analysis of defect clusters in heavy-ion irradiated silver and copper

The weak-beam technique has been used to investigate the geometry of point-defect clusters in silver and in copper produced by heavy-ion bombardment. It was found that many of the clusters could be identified as partially dissociated Frank loops, confirming the interpretation by Wilson and Hirsch (1972) of certain black-white contrast features. A model of dissociated loops in {111} foils is proposed which could explain the observed fine structure of the weak-beam images. The detailed geometry of this model arises due to the influence of surface image forces on the loop dissociation.