This study investigates the plastic deformation behaviors and dislocation structure evolutions of oxide single crystals (9. 8 mol% Y 2 O 3 -stabilized ZrO 2, Al 2 O 3, and SrTiO 3) subjected to shot peening at room temperature with varying pressures and durations. The deformation behaviors and subsurface microstructures were characterized via atomic force microscopy (AFM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Surface plasticity during shot peening was mediated by the activity of dislocations belonging to specific slip systems comparable to those operating in small-scale mechanical testing, such as micropillar compression, at quasistatic strain rates. The AFM and TEM observations indicated that the ZrO 2 specimens deformed through orientation-dependent slip mechanisms: 111 and 001 slips dominated during shot peening to the (001) and (111) surfaces, respectively; the Al 2 O 3 (0001) surface primarily deformed via 1 ¯ 102 rhombohedral slip; and the SrTiO 3 (001) surface deformed via 101 slip. The dislocation densities in the subsurface regions increased to an order of 10 13 –10 14 m −2 after shot peening. The dislocations introduced through shot peening also improved the post-mechanical properties, as characterized by indentation techniques. Crack shortening and hardness increase were strongly correlated with a higher dislocation density, as indicated by XRD peak broadening under harsher shot peening conditions. These results highlight the possibility of plastic forming in oxide ceramics by accumulating small-scale deformation and emphasize the significance of dislocation engineering for improving their mechanical properties.
Masuda et al. (Sun,) studied this question.