A new technique for measuring the separation of closely spaced dislocations using residual-contrast conditions

Abstract

In order to measure the spacing of closely spaced dislocations, a method with sufficient spatial resolution must be used. High resolution imaging provides one method of determining the spacing of paired dislocations, but care must be taken since these authors have shown that thin film effects can give rise to structures not present in bulk materials. To date, the most widely used method of determining the spacing of paired dislocations is the weak-beam dark field method. This method has proved extremely useful in the study of many systems, see Cockayne3 for a review. One of the difficulties of the weak-beam method is that the observed peak positions do not generally correspond to the actual position of the partial dislocation cores. Correlation of the peak positions with the true position depends on the deviation parameter, foil thickness, and position of the dislocations within the foil.