Mechanical properties of the low-temperature reactive melt infiltrated ZrB2–ZrC based composites

Abstract Zirconium diboride–zirconium carbide based composites were fabricated by reactive melt infiltration with boron carbide and Zr 2 Cu at 1200 °C. Mechanical properties of the composites before and after high temperature treatments were investigated. The presence of elongated ZrB 2 grains and amorphous residual alloy provided the composites with an excellent fracture toughness of 12.1 MPa m 1/2 . High temperature treatments could improve the density of sintered composite and increase the bonding strength between ZrB 2 and ZrC grains. This resulted in a flexural strength of 469.7 MPa and an excellent fracture toughness of 13.6 MPa m 1/2 was obtained after a treatment at 1600 °C in argon. The evaporation of copper at 1600 °C in vacuum during heat treatment caused degradation in the mechanical properties. However, at a higher temperature of 1800 °C, the composite showed the highest flexural strength of 484.1 MPa and the highest flexural modulus of 282.2 GPa, apparently counterbalanced the Cu-loss effect.