In situ studies on temperature‐dependent deformation mechanisms of Al₂O₃ prepared by spark plasma sintering

Alumina (α‐Al 2 O 3 ) is one of the most versatile engineering ceramics, and its mechanical properties have been extensively studied. However, the micromechanical properties of Al 2 O 3 with a fine microstructure are less well understood. Here, we present one of the first investigations that probe the micromechanical properties of fine‐grained polycrystalline Al 2 O 3 fabricated via spark plasma sintering, employing in situ microcompression tests inside a scanning electron microscope. This study explores the influence of temperature variations on the deformation mechanisms, particularly the involvement of microcracks and dislocation activities throughout the deformation process. As temperature rises, substantial deformability occurs in the inherently brittle Al 2 O 3 at intermediate temperature, where the improved plastic deformability mainly arose from prominent dislocation activities accompanied by grain boundary sliding. This study sheds light on understanding the relationship between defect evolution and mechanical behavior in Al 2 O 3 with fine grain sizes.