Microstructure evolution and plastic mechanism in deformation of bulk amorphous Al2O3-ZrO2-Y2O3

In this work, compressive deformation is performed on bulk amorphous Al2O3-ZrO2-Y2O3 at moderate temperatures. The amorphous samples display brittle fracture without any noticeable permanent strain at 500 °C. However, a large plastic strain of up to 15.1% is achieved at 600 °C. During the entire compressive deformation process, the samples remain amorphous, and shear bands start to form, accompanied by a stress drop. The amorphous AZY shows low Vickers hardness value of 2.8 GPa at 500 °C, and 2.2 GPa at 600 °C, due to the disordering microstructure. In the optical microscope images, local plastic deformation are detected around the indention without large cracks. Transmission electron microscopic observations and selected area electron diffraction analysis suggest that the shear band formation originates from the presence of free volume. Furthermore, the nucleation and propogation of shear bands lead to the large macroscopic plastic strain in the bulk amorphous Al2O3-ZrO2-Y2O3.