Structure Formation in Equimolar Mixture of HfC–ZrC–TiC–NbC Carbides

Structure formation during hot pressing of an equimolar powder mixture HfC–ZrC–TiC–NbC in the temperature range from 1400 to 1900°C is investigated. It is found that a monophase substitutional solid solution (Hf, Zr, Ti, Nb)C based on hafnium carbide forms at a temperature of 1700°C. It is shown that the formation of the ceramic solid solution (Hf, Zr, Ti, Nb)C proceeded in many stages with the formation of intermediate two- and three-component ceramic solid solutions (Hf, Zr)C, (Nb, Zr)C, and (Hf, Zr, Ti)C and their subsequent dissolution. The resulting ceramic multicomponent substitutional solid solution (Hf, Zr, Ti, Nb)C has improved mechanical properties compared to similar properties of initial carbides: E = (616 ± 77) GPa, H = (36 ± 8) GPa, and K1C = ( 3.4 ± 0.5) MPa ∙ m 1/2 .