Evaluation and comparison of the microstructure and mechanical properties of fibrous Al2O3–(m-ZrO2)/t-ZrO2 composites after multiple extrusion steps

Microstructural variations in the Al2O3–(monoclinic-ZrO2)/tetragonal-ZrO2 core/shell composites (Al2O3–(m-ZrO2)/t-ZrO2) were tailored using different volume fractions of the core and shell by the multi-pass co-extrusion process. To introduce continuously fibrous microtextures with varying dimensions of microstructure, various volume fractions of the Al2O3–(m-ZrO2) core and t-ZrO2 shell phases were used (40/60, 50/50 and 60/40). The effect of the number of extrusion passes on the control of microstructure and the corresponding compositeʹs mechanical properties were investigated. The bending strength and fracture toughness values were shown to increase as the t-ZrO2 shell volume fraction increased, which was unlike the Vickers hardness value. However, the fracture toughness value was higher for 4th pass composites compared to 5th pass composites due to the presence of the fibrous core/shell microstructure. In addition, the bending strength was higher for 5th pass composites. Detailed microstructural analysis was carried out by SEM.