Spark plasma sintering of (Zr,Nb)C ceramics

A range of (Zr,Nb)C ceramics containing 20–50 vol% NbC were spark plasma sintered at 2000°C. The ceramics had relative densities greater than 97 %, and all compositions formed a complete solid solution . The average grain size was ∼7.1 µm over all compositions. Elastic moduli values ranged from 436 to 445 GPa, and the fracture toughness ranged from 0.8 to 2.8 MPa·m 1/2 over the compositional range, both increasing with increasing NbC content. The hardnesses of the (Zr,Nb)C ceramics ranged from 19.1 to 20.2 GPa at a load of 9.81 N. The flexural strength increased from 352 to 395 MPa as the NbC content decreased from 50 to 20 vol%. The successful solid solution formation and densification of the (Zr,Nb)C ceramics provide a surrogate framework for substituting UC for the NbC to produce (Zr,U)C ceramics for nuclear applications. • (Zr,Nb)C ceramics were densified using spark plasma sintering. • Full solid solution was achieved. • (Zr,Nb)C microstructures were characterized. • Hardness, fracture toughness, flexural strength, and dynamic moduli were measured.