Effect of polarization on fracture toughness of BaTiO3/Al2O3 composites

In this study, Al2O3 based composites dispersed with BaTiO3 particles were fabricated by a conventional sintering process. The relative density and microstructure (grain size, phase) of composites were studied. The relative density of BaTiO3/Al2O3 composites decreased with increasing BaTiO3 content, and there were reaction phases between Al2O3 matrix and dispersed BaTiO3 particles. The Indentation Fracture Method was used to evaluate the fracture toughness of the present composites before and after polarization. It was verified that an applied electric field induced distinct anisotropy in fracture toughness of BaTiO3/Al2O3 composites between parallel and perpendicular directions to the poling direction. The fracture toughness was improved with addition of BaTiO3 particles to Al2O3 matrix. The toughening mechanisms of BaTiO3/Al2O3 composites have been also discussed.