Microstructure and Mechanical Properties of Spark Plasma Sintered TaC0.7 Ceramics.

The TaC_0.7 composition was spark plasma sintered (SPS) at 1600°-1900°C using TaC and Ta as the starting powders. Densification process, phase evolution, microstructure development, and the mechanical properties of the composites were investigated. The results indicated that the TaC_0.7 composition could be SPS to >95% of theoretical density in 5 min at 1600°C or above. The phase formation was associated with carbon diffusion from the starting particles TaC to Ta to form Ta₂C and Ta₆C₅ as intermediate phases, and subsequently the equilibrium phases of TaC _y and ζ-Ta₄C_{3− x}. The presence of lamellar ζ-Ta₄C_{3− x} regions enhanced the flexure strength (up to 972 MPa) and fracture toughness (up to 13.8 MPa·m^1/2). [ABSTRACT FROM AUTHOR]