Tougher and harder zirconia toughened alumina (ZTA) composites through in situ microstructural formation of LaMgAl11O19

Abstract Advanced ceramic materials are highly demanded for various modern industrial and practical engineering applications. Nonetheless, the requirement of attainment hard and simultaneously tough materials is a crucial matter for industrial sectors. To accomplish this target, the strategy of designing a novel microstructure of Zirconia Toughened Alumina (ZTA) ceramics was utilised through in situ formation of LaMgAl11O19 (LMA) based on the stoichiometry ratio of constitute oxides inside ZTA composites during sintering process. ZTA Samples were conventionally sintered at 1600 °C for 2 h to ensure fully formation of LMA while their characteristics were analysed using SEM-EDX and XRD. The LMA elongated grains significantly enhanced ZTAs' Indentation Fracture Resistance (KIFR) due to crack deflection and crack bridging mechanisms combined with transgranular and intergranular fracture modes. Additionally, higher hardness was obtained due to high LMA density, creation of low porous ZTA and strong interface bonding between LMA and ZTA grains. The KIFR was stable while the hardness was steadily declined due to more porosity accompanied by LMA in situ formation. Consequently, sustainable high hardness and enhanced KIFR of ZTA ceramics were achieved. The optimum outcomes were superior KIFR (7.8 MPa.m^1/2) and hardness (1660 HV) than the pure ZTA (5.9 MPa.m^1/2, 1568 HV). The investigation provides a new hint for future design and fabrication of economic and high performance ceramics through in situ formation of LMA according to the stoichiometric ratio of the reinforcing oxides.