Microstructure and mechanical properties of B4C-NbB2-SiC ternary eutectic composites by a crucible-free zone melting method

Abstract

Directionally solidified B4C–NbB2-SiC ternary composites were prepared by a floating zone method based on crucible-free zone melting of compacted powders. The ternary eutectic composition of B4C–15NbB2–35SiC (mol.%) was characterized by a boron carbide matrix, directionally reinforced by lamella-type NbB2 and SiC phases. NbB2 and SiC inclusions about 1−2 μm in thickness were uniformly dispersed in B4C matrix of B4C–NbB2–SiC eutectic composite. The Vickers hardness and indentation fracture toughness of the B4C–NbB2–SiC ternary eutectic were 35.8 GPa and 6.4 MPa m1/2, respectively.