Assessing the Fracture Toughness of Al₂O₃-Sm₂O₃ Ceramics for Different Sm₂O₃ Contents Using a Reliable Toughness Measurement Method: Single-Edge Precracked Beam

In this research, the effect of Sm2O3 in different volume ratios on the fracture toughness of Al2O3 prepared by dry pressing and pressureless sintering was investigated via a reliable toughness measurement technique, single-edge-precracked-beam method. During sintering, the reaction between Al2O3 and Sm2O3 resulted in the formation of SmAlO3 phase in various morphologies based on the Sm2O3 content, leading to significant grain growth in Al2O3. The grain sizes in Al2O3 reached up to 35 mu m when 0.8 vol.% Sm2O3 was present. The addition of Sm2O3 improved the fracture toughness of the ceramics, with samples containing 0.5 and 0.8 vol.% Sm2O3 exhibiting toughness values (6.6 +/- 1.0 MPam1/2 and 6.5 +/- 1.7 MPam1/2, respectively) which were approximately 70% higher than the pure Al2O3 (3.8 +/- 0.2 MPam1/2). The enhanced fracture toughness was attributed to the grain bridging of large Al2O3 grains, frictional energy dissipation by the pull-out of large Al2O3 grains, and pull-out of SmAlO3 phase particles. It was observed that the introduction of Sm2O3 into Al2O3 at specific ratios altered the microstructure, effectively increasing the toughness of the material. This toughness improvement is particularly valuable for structural applications in which high fracture toughness is essential such as biomedical and armor components.