Geometrical factors influencing the orientations of dipolar dislocation structures produced by cyclic deformation of f.c.c. metals

Abstract

A recently proposed geometrical model to explain the orientations of labyrinth dipolar walls produced by cyclic deformation of f.c.c. metals is extended to explain the orientations of loop patches, channels within the matrix structure, and dipolar walls within persistent slip bands. The model is based on determining favourable stacking arrangements for dipolar loops involving one or two Burgers vectors and slip systems and on determining the directions in which stacking should be limited. The stacking of dipolar loops into regular networks results evidently in low energy dislocation structures. The dipolar loops are assumed to be swept into the dipolar dislocation arrangements by edge dislocations. When excess dipolar loops of one slip system are present, the ability of the dipolar arrangements to accommodate these becomes important. Good agreement is found between the predictions of this model and the available experimental evidence.