The oxygen content during the intermediate and final stages of sintering can have a strong effect on the microstructural evolution of oxide fuels. Two depleted urania (d-UO2.0 and d-UO2.14 samples, sintered up to a theoretical density of 90%, were serial sectioned using a focused ion beam and characterized with electron backscatter diffraction (EBSD). The EBSD data were used to make three-dimensional reconstructions of the microstructures to evaluate their characteristics at an intermediate stage of sintering. The oxygen content was found to affect grain shape and grain boundary (GB) mobility, as curved and elongated grains were observed in UO2.0., as well as stronger pore-GB interactions, which is an indication that microstructure was less evolved in UO2.o Both samples presented a similar fraction (=20%) of special, coincident site lattice boundaries, with larger amounts Ε3n GBs, and a rather large fraction of Ε11 GBs for UO 2.14- Crystallographic GB planes were also determined to study the distributions of all GB parameters. The UO 2.0 sample had a large fraction of GB planes close to the Ε3 twinning planes, which suggests that lowerenergy interfaces are used to minimize energy in this sample, potentially due to lower overall GB mobility as compared to UO2.14.
- Microstructure evolution
- Oxide fuels
- Oxygen stoichiometry
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Nuclear Energy and Engineering
- Condensed Matter Physics