Dislocation microstructure evolution: Enabling the analysis of experimentally measured structures within a discrete dislocation dynamics modelling framework
Final Report Abstract
Enabling the analysis of experimentally measured dislocation structures within a discrete dislocation dynamics modelling framework is quite a challenging task. A scheme was established covering all steps: TEM imaging; two reconstruction routes for geometrical information based either on classical dislocation analysis or on two view reconstruction techniques which are nowadays used in machine vision. In the current status the classical reconstruction gives more precise geometrical information. During the analysis of the deformed Al samples, the most examined structure turned out to be very interesting: the selected structure - consisting of two triple nodes and attached dislocation - could only be rationalized by the presence of glissile reactions. This particular structure is therefore considered as a first indirect experimental evidence for glissile reactions. The observation supports therefore also the conclusion on the importance of this reaction type for dislocation multiplication / generation drawn from large scale DDD simulations. In these simulations it was shown, that dislocation generation and dislocation density increase are mainly caused by glissile reactions. Furthermore, simulations starting from the experimental structure show the transformation of pinned triple node to a sliding node shared by two dislocations on different glide planes. An analysis of a large scale DDD simulation with respect to the probability of formation of such nodes showed that they are quite common.
