Attempt to correlate dislocations network and distribution to macroscale plane rotations in <001> cast-mono ingots
Résumé
This work aims to contribute to the understanding of the mechanisms behind electrically
active crystalline defect formation in cast-mono (cm) ingots grown along the <001> axis. Both
the spatial distributions of background dislocations in the cellular dislocation array and the driving
force for dislocation multiplication in the sub-grains are not perfectly understood. Macroscale
length crystal rotations are here characterized by the ($\theta$/2θ) X-ray diffraction (XRD) method at
different ingot heights and along two perpendicular sample axes. XRD measurements show the
presence of crystal rotations in the large single grain domain. Two orthogonal misorientations
components are found to evolve linearly along each sample axis forming plane orientation
gradients up to (0.05±0.02) degree/cm extending over 12 cm inside the cast-mono grain. (001)
crystal structure deformation are also analysed by rocking curve imaging (RCI) using synchrotron
radiation on wafers of a neighboring brick. First, results confirm the presence of the plane
orientation gradient measured by XRD and its order of magnitude. Second, RCI results
demonstrate that the plane orientation gradient is associated to the cellular dislocation network.
Therefore, these results strongly suggest that background dislocations network of a cellular form
can create an organized orientation gradient at large distance within the ingot. The involvement
of the characterized orientation gradients in the formation and extension of electrically active
SGBs in cast-mono ingots is discussed.
Domaines
MatériauxOrigine | Fichiers produits par l'(les) auteur(s) |
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