Abstract:
(LaNbO4+ZrO2)/MoSi2 composite ceramics were prepared by hot-pressing sintering.The microstructure and fracture characteristics of composites were analyzed by means of scanning electron microscope,image analysis instrument and X ray diffractometer.The microhardness,grain size,porosity and fracture toughness were measured.The grain of (LaNbO4+ZrO2)/MoSi2 composite sample is obviously fine compared with that of MoSi2 sample.The compactness of composite is excellent with microhardness increased.LaNbO4 assist with ZrO2 particles caused the change from transgranular to intergranular fracture mechanism,which greatly improved the toughness of MoSi2.These might be related to the fine crystal grain,improved compactness,phase transfer toughening,crack deflect,microcrack toughening of ZrO2 nanoparticles and domain structure transfer of LaNbO4 particles.