Effects of MoSi2 additions on the properties of Hf– and Zr–B2 composites produced by pressureless sintering

Composites in the HfB2–(5–20 MoSi2) system were produced from powder mixtures and densified through pressureless sintering at 1950 °C. Microstructure and mechanical properties were compared with pressureless sintered ZrB2-based composites containing the same amount of MoSi2. The addition of MoSi2 allowed the achievement of highly dense bodies without degrading the high-temperature behaviour. Flexural strength measured at 1500 °C in air were in the range of 480–580 MPa.