High entropy carbide ceramics from different starting materials

Three typical ceramic processing were respectively used to synthesize (Ti0.2Zr0.2Nb0.2Ta0.2W0.2)C high-entropy carbide (HEC) ceramics by spark plasma sintering. Although single-phase composition characterized by X-ray diffraction were obtained by the three processes, the microstructures and elemental distributions are different. The reasons for the formation of these features are preliminarily discussed. The results demonstrate that the particle sizes of the starting metallic powders was a key factor for obtaining a homogeneous distribution of each elements in the HEC. Carbide process with relatively finer starting carbide powders compared to the above metallic starting powders resulted in an NEC with homogeneous distribution of elements, but the obtained ceramics showed the lowest relative density. For oxide process, it is considered that the obviously higher reaction temperature between ZrO2 and graphite resulted in a two-phase structure of an HEC and a zirconium-rich phase, but the obtained HEC showed the highest relative density.