Creep behavior and related structural defects in Al2O3–Ln2O3 (ZrO2) directionally solidified eutectics (Ln = Gd, Er, Y)

The eutectic architecture of “in situ” composites prepared by solidification from the melt in the Al2O3–Ln2O3 (ZrO2) systems gives rise to materials with a high creep resistance. With the objective to elucidate the high temperature deformation micro-mechanisms, microstructural features are investigated on crept specimens. Compressive creep experiments have been carried out between 1400 and 1550 °C for various eutectic compositions. Different deformation regimes depending on considered systems and conditions of stress and temperature are revealed. Transmission electron microscopy studies emphasize the activation of different slip systems in the alumina phase and the deformation by dislocation climb processes controlled by bulk diffusion.