Synthesis of highly dispersed super-refractory tantalum-zirconium carbide Ta4ZrC5 and tantalum-hafnium carbide Ta4HfC5 via sol-gel technology

Nanocrystalline powders of super-refractory complex carbides Ta4HfC5 and Ta4ZrC5 were synthesized using a hybrid method comprising sol-gel technology for preparing highly dispersed metal oxidescarbon starting mixtures and a relatively low-temperature (1300-1500A degrees C) carbothermal synthesis under a dynamic vacuum (P = 1 x 10(-3) to 1 x 10(-5) MPa). The elemental and phase compositions of the products and average crystallite sizes were determined. TEM was used to study particle morphology and dispersion. Microstructures were observed by SEM. BET specific surface areas were determined for powders prepared at 1400A degrees C.