Phase transition of multi-component (TiZrVNb)C ceramics—Part I: Phase decomposition induced by carbon content

The phase decomposition can enhance the mechanical properties of carbide ceramics effectively, which can overcome the difficulty of enhancement of mechanical properties for single-phase multi-component carbide ceramics. In this work, a series of non-stoichiometric (TiZrVNb)C_x ceramics were prepared by spark plasma sintering (SPS) at different temperatures. The effects of carbon content on phase compositions, microstructure evolution, and mechanical properties were investigated in detail. The phase decomposition took place with the reduction of carbon content. Two different solid solutions of (Ti, V)-rich and Zr-rich phases formed originating from the decomposition of equimolar single-phase solid solution, namely the Zr-poor phase and Zr-rich phase, respectively. The distribution of Nb element is relatively uniform. The semi-coherent interfaces between the Zr-poor phase and the Zr-rich phase can harden and strengthen effectively under the synergistic effect of grain refinement. The ceramics with phase decomposition structures have apparent advantages compared to single-phase high-entropy carbides. This work provides an important train of thought for the microstructure tailoring and properties optimization of multi-component carbide ceramics.