The contrast on electron micrographs caused by closely spaced edge dislocation multipoles

The electron microscopic contrast which would be produced by arrays of parallel dipoles consisting of dissociated dislocations is examined. It is found that a multipole can, to a good approximation, be considered as a planar fault with the result that a multipole gives rise to fringes similar to stacking-fault fringes. Comparison between the calculated fringes and those observed in deformed Cu-Al alloys indicates that many of the observed fringes are caused by closely spaced dislocation multipoles.