A correlation of periodicities in diffraction patterns and images from a grain boundary

Abstract

Suitably defocused and exposed electron diffraction patterns from a high-angle grain boundary in a polyerystalline Cu—Si alloy contain rows of multiple diffraction spots along two different directions at a small angular separation. These occur in association with the main reflections from the grains. Geometrical analysis of the observed diffraction effects shows that they can be related to structure in the boundary. Furthermore, a correlation between diffraction patterns and bright-field electron micrographs enables fringe systems in the images of the boundary to be related to the boundary structure.

The results are discussed in terms of a model involving arrays of secondary dislocations which accommodate the departure of the observed misorientation between the two grains from that of a nearby coincident site lattice.