Synthesis of a TiB₂-TiC Composite by Reactive Spark Plasma Sintering of B₄C and Ti

Abstract

A composite of TiB₂ and TiC was synthesized from B₄C and Ti powders by spark plasma sintering accompanied with the solid-state displacement reaction of them. In the early stages of the reaction, TiB, TiB₂, Ti₃B₄, and TiC were formed as reaction. products, and finally they were changed completely into TiB₂ and TiC. Relative density of composites reached more than 99 % at 1800°C and above. At 1800°C and below the composites had unique microstructure; TiB₂ phases formed networks surrounding TiC phases. The network structure disappeared at higher temperatures, and TiB₂ phases were dispersed more homogeneously in TiC phases. The composites obtained at 2000°C had mechanical properties of Young's modulus 514 GPa, Poisson's ratio 0.18, Vickers hardness 2090 and fracture toughness 3.8 MPa m^0.5