Phase Composition‐Controlled Synthesis, Microstructure, and Properties of TiB ₂ –TiC Composite

ABSTRACT TiB 2 –TiC composite ceramics were synthesized by boro/carbothermal reduction of oxides and densified by spark plasma sintering. Thermodynamic processes within the reaction system were discussed, and phase diagrams were constructed to guide formulation design. In addition, the phase constituents, impurity content, micromorphology of the powders and densification, mechanical properties, and oxidation resistance of the composite ceramics were studied. The results indicate that reasonable adjustment of carbon content can effectively regulate the phase content in the composite ceramics, allowing for adjustable TiB 2 content within the range of 35–75 wt%. Additionally, it suppresses excessive grain growth of boride, maintaining the grain size of both phases at approximately 200 nm and reducing the residual C and O impurities. When the ratio of TiB 2 :TiC in the powder is 64.1:35.9 wt%, the grain sizes of the two phases are most similar, resulting in the highest density of sintered TiB 2 –TiC composite ceramics, reaching 99.78%. The corresponding Vickers hardness can reach 24.07 ± 0.53 GPa.