The dissociation of super-dislocations in Ni3Al, which had a pure screw character, was recorded on weak beam images at the g(5g) imaging condition. All screws were observed to dissociate on an {001} habit plane bounding AFB faults. By computer modelling, the dissociation distance (dCSF) of the Shockley partial dislocations that bound a complex stacking fault was shown to be less than 1.5nm. This was the first reported case of fourfold dissociation bounding CSF+APB+CSF faults with a non-planar configuration and pure screw character. The energy values deduced from the measured spacing show quite large difference from the results obtained from dissociation with a planar system. It was questionable to use the linear anisotropic elasticity theory for such small splitting and non-planar configuration. In addition, the simulations demonstrated that a g(ng) condition was a good choice for imaging partial separation.

Weak Beam Observations of Dissociation of Pure Screw Dislocations in Ni3Al. Meng, X., Preston, A.R.: Journal of Materials Science, 2000, 35[4], 821-8