Enhanced high-temperature strength of HfB2-SiC composite up to 1600°C

Using B4C and C additives, a HfB2-SiC composite with an enhanced strength up to 1600 °C was prepared using high-energy ball milling followed by hot pressing. The composite microstructure comprised equiaxed large HfB2 and fine SiC grains and an intergranular amorphous phase. The mechanical behaviour of the composite was evaluated up to 1600 °C via a four-point bending test. At or below 1500 °C, only a linear stress-strain response was observed. At 1600 °C, however, the initial linear response was followed by nonlinear deformation behaviour. The flexural strength was constant between room temperature and 1400 °C; subsequently, the flexural strength significantly increased with increasing temperature up to 1600 °C, with strengths in the range of 650-750 MPa.