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Microstructural evolution at 1450°C of two 3 mol% Y20J-Zr02 tetragonal polycrystals (Y-TZP) containing different residual impurity amounts has been investigated by analytical and scanning electron microscopy in order to clarify the role of the amorphous intergranular phases. Phase partitioning is interpreted as a process based on dissolution/reprecipitation reactions involving mass transport via the liquid impurity phase. Grain growth is inhibited by yttria migration before the phase equilibrium is reached, then increases drastically. [

The neutron absorbing ceramic boron carbide was irradiated in the Phenix fast breeder reactor between 600 and 1500 °C. Selected pellets were observed at different magnifications using optical ceramography, scanning electron microscopy, and transmission electron microscopy. The bulk swelling was measured as a function of the burn-up and compared to a recent model based on microstructural observations. Intergranular microcracking was identified as the main source of troubles in the use of boron carbide at high fluence levels and studied in relation with our recent models.

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