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 °C. Further increase in testing temperature, i.e. up to 1900 °C, was accompanied by a slight decrease in strength. Such behavior was attributed to increased contribution of the plastic deformation to the fracture process.