Electron irradiation induced vitrification at dislocations in quartz
Recent observations using the ‘weak beam’ electron microscopy technique of split images of dislocations in quartz have been interpreted as arising either from dissociation of the dislocations into partials1, or from a glassy (metamict) phase at the core2, resulting from irradiation damage. In this letter we describe observations of lattice images of near end-on dislocations in quartz, which enable us to distinguish between these two models.
Effect of elastic distortions on solid-state amorphization at grain boundaries and dislocations
Two theoretical models are proposed, which describe solid-state amorphizing transformations at, respectively, grain boundaries and dislocations in crystalline solids. In the framework of the former model, the driving force for the formation of an amorphous intergranular layer is revealed and estimated, which is related to changes in the elastic energy density of a conventional grain boundary that transforms into the amorphous layer. The second model describes nucleation of the amorphous phase at the cores of lattice and interfacial dislocations as a process associated with the special splitting of such dislocations. In the framework of the model, the special role of elastic distortions in solid-state amorphization at dislocation cores is revealed and examined.
SR topography of plastically deformed Fe-Si bicrystals - observation in situ and post mortem
SR reflection topography was applied to study the interaction of slip dislocations with the grain boundaries in Fe-4at%Si bicrystals deformed by compression. Three experimental settings with either a white or monochromatic beam were used and the corresponding orientation contrast analysed. Dislocation transmission through the grain boundary was observed in bicrystals with favourable geometry of the slip systems.