Mechanical, electrical and thermal properties of HfC-HfB2-SiC ternary eutectic composites prepared by arc melting

• The ternary eutectic composition of 16HfC-17HfB 2 -67SiC (mol%) and the eutectic temperature of 2760 K was first identified. • The HfC-HfB 2 -SiC ternary eutectic composite had higher microhardness and fracture toughness than the composites prepared by sintering. • The HfC-HfB 2 -SiC ternary eutectic composite showed excellent electrical and thermal conductivity, which is beneficial for its application. HfC-HfB 2 -SiC composites were prepared by arc melting using HfC, HfB 2 and SiC powder as raw materials. The ternary eutectic composition of 16HfC-17HfB 2 -67SiC (mol%) was first identified, showing a complicated maze microstructure of HfC, HfB 2 and SiC approximately 500 nm in thickness. The eutectic temperature of the HfC-HfB 2 -SiC composite was nearly 2760 K. The Vickers hardness and fracture toughness of the HfC-HfB 2 -SiC ternary eutectic composite were 20.8 GPa and 7.7 MPa m 1/2 , respectively. With increasing temperature from 300 to 800 K, the electrical conductivity decreased from 8.8 × 10 5 to 4.3 × 10 5 Sm −1 , whereas the thermal conductivity increased from 28 to 32 W m −1 K −1 .