Combinative effects of Y2O3 and Ti on Al2O3 ceramics for optimizing mechanical and electrical properties

This study aims to combine Y2O3 and Ti to improve the mechanical and electrical properties of Al2O3 ceramics. Al2O3-based composites containing 20 vol% of metallic Ti were chosen. Y2O3 was used as the effective additive to optimize the mechanical and electrical properties of Al2O3/Ti composites. The effects of Y2O3, ranging from 1 to 5 wt%, on mechanical and electrical properties of Al2O3/Ti composites were studied. Energy-dispersive X-ray spectroscopy indicated that the added yttrium was present at the grain boundaries. The formation of yttrium aluminum garnet (Al5Y3O12, YAG) resulting from the solid-state reaction between Y2O3 and Al2O3 was identified by X-ray diffraction (XRD). All Y2O3 doped Al2O3/Ti composites showed an increase in the density. The observation of microstructure revealed that the microstructure was refined and the grain size of Al2O3 decreased. Vickers hardness, Young's modulus, and fracture toughness of the c6mpoSite having Y2O3 content of 2 wt% reached their maximum values, which were 15.2 GPa, 355.2 GPa, and 4.5 MPamv2, respectively. Ductile fracture mode and transgranular fracture were visible in all the composites. The toughening mechanism, which arises due to the presence of YAG, was demonstrated. In addition, the electrical resistivity of composites increased monotonically with an increase in the Y2O3 content. Nevertheless, the increase was negligible and the composites could be regarded as a good electrical conductor having 5 wt% Y2O3 addition.