Comparative study of reactive and nonreactive spark plasma sintering routes for the production of TaB₂-TaC composites

The influence of two different spark plasma sintering (SPS)-based processing routes (i.e., reactive SPS [RSPS] and nonreactive SPS) on the properties of TaB₂-TaC composites was investigated. Ta₂O₅ and B₄C powders were used as starting materials in the RSPS method, and synthesis and densification of TaB₂-TaC composites were accomplished in a facile single step. The effect of sintering temperature and time on the microstructure and densification of the in-situ RSPS were investigated. The obtained results were compared with nonreactive spark plasma sintered TaB₂-TaC composites. The highest densification (∼99.5%) was achieved for the TaB₂-TaC composite with 6.64 vol.% TaC after reactive sintering at 1550°C under 40 MPa with a 5 min holding time. Although lower SPS temperature was used in the RSPS method, better densification and higher Vickers hardness were obtained compared to the nonreactive SPS. While platelet-shaped TaC formation was observed in both processes, the average grain size was smaller in the RSPS method. On the other hand, no significant difference was detected in the oxidation behavior of the composites produced by RSPS and nonreactive SPS.