Phase transition of multi-component (TiZrVNb)C ceramics—Part II: From single phase to multiple phases via adjusting V content
Qingyi Kong, Lei Chen, Sijia Huo, Kunxuan Li, Wenyu Lu, Yujin Wang, Yu Zhou
Abstract
To address the relatively mediocre mechanical properties of single-phase multi-component carbide ceramics, a phase transition from a single phase to multiple phases was proposed to achieve superior mechanical properties. A series of (TiZrV<sub><i>x</i></sub>Nb)C<sub>0.8</sub> ceramics with different V contents were fabricated by spark plasma sintering (SPS). The influence of the V content on the phase composition, microstructural evolution, and mechanical properties was investigated in detail. The transition behavior from a single phase to multiple phases is discovered and discussed. The formation of the Zr-rich phase and Zr-poor phase can be attributed to the increase in lattice distortion and mixed enthalpy caused by the addition of V. A nanometer lamellar structure with a semi-coherent interface obtained via <i>in</i> <i>situ</i> decomposition is reported for the first time in multi-component carbide ceramics. The semi-coherent interfaces with high dislocation density and strain concentration effectively improve the mechanical properties, grain refinement, and multi-phase formation. The optimal comprehensive mechanical properties of the Vickers hardness (26.3 GPa), flexural strength (369 MPa), and fracture toughness (3.1 MPa·m<sup>1/2</sup>) were achieved for the sample with 20 mol% V.