Mechanical properties of SiC-NbB2 eutectic composites by in situ spark plasma sintering

The in situ synthesis/consolidation of SiC-NbB2 eutectic composites by spark plasma sintering (SPS) is reported. The SPS processing resulted in composites with eutectic structure and hardness of 25-31 GPa. Screening of experimental data suggested that eutectic composition in this system is 37-39 vol% NbB2. The temperature dependence of the flexural strength of the SiC-NbB2 system has been reported for the first time. Ceramic composites with eutectic structure exhibited an unchanged strength of 610 +/- 25 MPa at room temperature and at 1600 degrees C. Further increase in testing temperature, i.e. up to 1900 degrees C, was accompanied by a slight decrease in strength. Such behavior was attributed to increased contribution of the plastic deformation to the fracture process.