The Shape of Frank Loops Studied by High-voltage Microscopy

Abstract

It is shown that extrinsic Frank loops exist in two different forms: one has < 1 1()> edges and sharp corners; the other has < 112) edges and rounded corners. The former results from growth of the loop, and is stabilized by dissocitation of the dislocation core. The latter form results from shrinkage of the loop, and is stabilized by the elastic energy of the dislocation. The observations imply that the absorption of vacanc ies by a loop occurs by a rate –controlling process different from the absorption of interstitials.