Reactive sintering behavior and enhanced densification of (Ti,Zr)B2-(Zr,Ti)C composites

Abstract Reactive hot pressing was used to prepare (Ti,Zr)B2-(Zr,Ti)C composites from equimolar ZrB2 and TiC powders. The reaction and solid-solution coupling effect and enhanced densification in ZrB2-50 mol.% TiC were proposed as contrasted to conventional consolidation of TiB2-50 mol.% ZrC. The (Ti,Zr)B2-(Zr,Ti)C composite sintered at a temperature as low as 1750 °C exhibited negligible porosity and average grain sizes of 0.30 μm for (Ti,Zr)B2 and 0.36 μm for (Zr,Ti)C. Complete reaction and rapid densification of ZrB2-50 mol.% TiC was achieved at 1800 °C for only 10 min. The densification mechanism was mainly attributed to material transport through lattice diffusion of Ti and Zr atoms with an activation energy of 531 ± 16 kJ/mol. This study revealed for the first time novel insights into rapid densification of refractory fine-grained diboride-carbide composites by reactive hot pressing at relatively low temperatures.