Structure and properties of (Ta1-хZrх)C and (Ta1-хHfх)C solid solutions produced by SHS and hot pressing.

Self-propagating high-temperature synthesis (SHS) from elements in combination with high-energy ball milling of the reaction mixture enabled the production of powdered (Ta 1-х Zr х)C and (Ta 1-х Hf х)C solid solutions with various stoichiometry and average particle size d 50 = 9 μm. Hot pressing (HP) was used for powders consolidation. All samples were found to be single-phase ones with lattice parameters following a linear function of the solid solution composition. The resulting dense samples of (Ta 1-х Zr х)C and (Ta 1-х Hf х)C solid solutions showed a notable growth of hardness and Young's modulus in comparison with ТаС carbide. The solid solution strengthening effect involving increase mechanical properties with growing content of Zr and Hf was confirmed. Temperature dependence of heat capacity, thermal diffusivity, thermal conductivity, and electric resistance was measured. Both Zr-and Hf-doped carbides showed high resistance to plasma torch impact at a temperature up to 3000°С. The high resistance towards ultra-high-temperature oxidation and erosion is provided by as-forming oxycarbide layers with high adhesion to the carbide matrix. [ABSTRACT FROM AUTHOR]