Sub-boundaries induced by dislocational creep in uranium dioxide analyzed by advanced diffraction and channeling electron microscopy - Archive ouverte HAL Access content directly
Journal Articles Materials Characterization Year : 2017

Sub-boundaries induced by dislocational creep in uranium dioxide analyzed by advanced diffraction and channeling electron microscopy

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Abstract

The network of sub-boundaries formed in a sintered UO 2 pellet after dislocational creep was examined. Very low angle boundaries, down to 0.1°were reliably detected by Electron BackScattered Diffraction (EBSD). This angular resolution was achieved by optimizing EBSD data collection and processing. Moreover, Accurate-Electron Channeling Contrast Imaging (Accurate-ECCI) was able to image the dislocations produced by creep, directly on the bulk sample. The dislocations were mostly organized in sub-boundaries with low energy configurations. Only a limited number of isolated dislocations were observed. Finally, the deformation substructure obtained after 8% creep deformation (at 1500°C under a 50 MPa uniaxial state) was quantified. The original grains with a mean size of 20 μm were in average fragmented in sub-grains of about 5 μm. The geometrically necessary dislocations density (GND) was evaluated from the filtered EBSD data to 7.9 × 10 12 m − 2. This value was 10 times higher than that measured on the as-sintered sample. This confirms that the GND density calculation is sensitive to the dislocation increase after 8% deformation by creep.
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Dates and versions

hal-03044975 , version 1 (22-02-2021)

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M. Ben Saada, Nathalie Gey, B. Beausir, X. Iltis, H Mansour, et al.. Sub-boundaries induced by dislocational creep in uranium dioxide analyzed by advanced diffraction and channeling electron microscopy. Materials Characterization, 2017, 133, pp.112-121. ⟨10.1016/j.matchar.2017.09.023⟩. ⟨hal-03044975⟩
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