Weak beam transmission electron microscopy imaging of superdislocations in ordered Ni3Al

In order to provide quantitative information about dissociation modes of superdislocations in ordered Ni3Al, weak-beam transmission electron microscopy observations of dislocation core structures have been combined with image simulations. The use of image simulations allowed us to interpret intensity peaks on weak-beam micrographs in terms of actual partial dislocations and splitting distances, and corresponding fault plane energies could be subsequently inferred. A description of the main parameters to be considered in the calculations is given below and the validity of such calculations is discussed in a critical way. The impact of these results on interpretation of the anomalous flow stress behaviour in Ni3Al is also addressed.