Interpretation of Dark Field Electron Micrographs of Carbon Fibres

Abstract

WHEN viewed under (002) dark field conditions, thin sections of carbon fibres appear to be composed of a number of undulating microfibrils running approximately parallel to the fibre axis. These microfibrils have alternating light and dark areas along their length and this cross-banding has not been explained entirely satisfactorily. Early investigators1,2 ascribed the cross-banding to the presence of twist and tilt boundaries along the microfibril. Direct lattice resolution of the individual basal planes in each ribbon by interference electron microscopy has, however, indicated that they are continuous for considerable distances along the fibre3,4 and so the explanation based on the existence of twist and tilt boundaries has had to be abandoned.