Many-beam contrast effects of dislocations

Abstract

The method of computation of electron microscope images of dislocations developed by Head (1967) for the two-beam case is extended to the many-beam case of electron diffraction. For 100 kv microscopy the application of such computations will consist primarily of taking into account higher systematic reflections but the good agreement that was obtained in some non-systematic many-beam cases serves to prove the quality of the method and in high-voltage microscopy many-beam computations will become indispensable. The contrast of pure screw dislocations in α-iron was investigated for some specific three-beam cases at 100 kv and a reasonable agreement between experimental and theoretical micrographs was obtained.