Microstructure and fracture behaviour of ZrO₂ (2 mol % Y₂O₃) reinforced with SiC whiskers

The microstructure, mechanical properties, fracture behaviour and toughening mechanisms of 20 vol % SiC_w-ZrO₂ (2 mol % Y₂O₃) composite were investigated by X-ray diffraction, scanning and transmission electron microscopies, energy dispersive analysis of X-rays, high-resolution electron microscopy techniques and the three-point bending test. The results show that the ZrO₂ (2 mol % Y₂O₃) matrix is well strengthened and toughened by 20 vol % SiC_w. The SiC whiskers are directly bonded to the matrix with no interfacial reaction layer or amorphous phase. The main toughening mechanisms of the composite are crack deflection, dynamic tetragonal to monoclinic ZrO₂ transformation, whisker pull-out and crack bridging. In addition, the fracture behaviour of the composite was observed using an in situ fracture technique.