Zirconia Toughened Alumina (ZTA) composites are widely used in both emerging and established industries due to their high hardness, excellent wear resistance, and high hot hardness. However, their inherent brittleness limits their applications, which can be addressed by incorporating softer phases inside hard ceramic matrices. Hence, in this study, different weight percentages of CeO₂ (ranging from 0 to 20 wt.%) as soft phases were added to ZTA matrices to investigate the resulting changes in microstructure, phase transitions, and physical properties. Investigation starts with synthesis of ZTA/CeO₂ obeying co-precipitation method. After development of composites morphological evaluation i.e. XRD & FESEM for all samples were thoroughly carried out. The analysis indicated continuous increase in tetragonal phases of zirconia with incorporation of CeO₂ particles, strongly supporting the transformation toughening phenomenon. The maximum hardness obtained as15.19 GPa, for 5 wt.% CeO₂, whereas, maximum toughness obtained as 5.73 MPa.m^1/2 for 20 wt.% CeO₂. The decrement with higher percentage of CeO₂ attributed to the formation of larger grain size and porosity inside the composites. In addition, the transform toughening phenomenon also contributed to improvement in physical properties especially toughness of the composites.

Keywords: Ceria (CeO₂), Zirconia Toughened alumina (ZTA), Hardness and fracture toughness.