Metadislocations in approximants of icosahedral intermetallic phases – METADIS

The present project is a contribution to the contruction of a general framework for understanding the atomistic mechanisms of high temperature deformation in complex intermetallic phases. It is based on the notion of metadislocation - that is a defect similar to an usual partial dislocation in crystals- that can be modelled as being the residue in a periodic approximant of a quasicrystalline perfect dislocation in the parent quasicrystal. The projects is two-fold :
- a theoretical work of N-dim description of the quasicrystalline and derived approximants, and the dislocations and metadislocations and calculations of the corresponding diffraction amplitudes in dynamical theory of fast electrons to compute the images ;
- an experimental work of elaboration of approximants of quasicrystals and usual characterization by X-ray powder diffraction and electron microscopy followed by a study of the metadislocations by standard technics and high resolution and finally studies of dislocation dynamics by in situ transmission electron microscopy