While the mechanisms of dislocation motion are well understood in most metals and our focus is on understanding the intricate effects of alloying, in intermetallics there are fundamental gaps in our understanding of how dislocations move through the more complex crystal lattices. For example, in Laves phases, synchroshear is known to occur in the so-called triple layer. However, under which conditions dislocations may move in the adjacent plane between triple and kagome layer instead - as the crystal structure is changed slightly or the phase becomes off-stoichiometric - is not yet known. Similarly, anti-site defects abound in addition to vacancies in these ordered phases and while many studies have measured their effects on properties, such as hardness, few attempts have been made to connect these with dislocation motion at the atomic scale.

In this presentation, we will investigate how the effects of changing crystal structure and stoichiometry can be investigated using nanoindentation, microcompression, conventional and high resolution TEM and atomistic simulations of the underlying dislocation mechanisms. We will show that point defects can assist dislocation motion in thermally activated processes at the dislocation line and that dissociation of dislocations and their exact slip plane can in fact be strongly affected by small changes in composition.