Complex Frank Loops and Fault Climb

Abstract

The Burgers vectors of the dislocations bounding steps in the stacking fault in Frank dislocation loops in quenched silver and copper-aluminium alloys have been identified by comparison of experimental electron microscope images and images computed using the Head-Humble technique. The steps in the fault are generally acute, faulted, and bordered by t<llO) stair-rod dislocations. However, obtuse unfaulted steps bordered by t<1l2) Shockley dislocations have also been observed. A characteristic configuration for a stepped loop consists of a triangular region within the main loop with one edge, a dissociated Frank dislocation, forming an edge of the main loop, and the other two edges, acute fault bends bordered by t<llO) dislocations, forming steps in the fault.