Preparation and elastic–plastic indentation response of MgAlON transparent ceramics

MgAlON transparent ceramic was prepared via pressureless sintering and post hot isostatic pressing. The in-line transmittance of MgAlON ceramic exceeds 80% in the range 0.39–4.67 μm, and the ceramic was fully dense with average grain sizes ∼55 μm. The mechanical properties at the grain boundary (GB) and the center of the grain (CG) of MgAlON ceramic was investigated by nanoindentation at forces of 1 × 102–3 × 105 μN. The results indicated that the hardness values of MgAlON ceramic were sensitive to the testing forces and measurements position. The hardness at GB zone was lower than that at CG zone, which was probably ascribed to weaker interatomic bonding force in GB area. The Meyer's index of the hardness in GB and CG regions is 1.87 and 1.82, respectively. There is a weaker ISE in GB area of MgAlON as a result of larger plasticity and smaller elasticity. The hardness values of GB and CG regions are ∼13.36 GPa and ∼13.58 GPa, respectively.