High-Entropy Carbides: Processing And Characterization

High entropy carbides (HEC) are multi-metal carbides involving at least five types of metal atoms at near-equal concentrations. They exhibit crystalline periodicity and a precise carbon sublattice but display disorder in terms of metal cation packing, therefore, they also have unconventional mechanical and physical properties. Up till now, the high entropy carbide compositions presented in literature have been rich in critical raw materials (CRM), such as hafnium (Hf). We explore the feasibility of fabricating sustainable high-entropy carbide compositions, free of CRMs, using conventional ceramic processing techniques, such as mechanical milling and thermal treatments. Five compositions of multi-metal carbides were chosen based on their entropy forming ability from literature. Metal powders and carbon were mixed in stoichiometric proportions using ball milling and sintered at high temperatures (2000 ºC). X-ray and electron microscopy techniques were used to characterize the materials and verify the formation of single-phase multi-metal carbides and chemical homogeneity at micrometer length scales. In addition, the mechanical properties of a selected composition was studied using nanoindentation.