Characteristic properties of combustion and structure formation in the Ti-Ta-C system

Abstract

Macrokinetic characteristics of the combustion of mixtures in the (100% − X)(Ti + 0.5C) + X(Ta + C) system with a variable mixing parameter X and initial temperature T0 of charge heating are considered. For compositions with X = 10 and 30%, an abrupt increase in the velocity Uc and temperature Tc of combustion as a result of passing two parallel chemical reactions of titanium and tantalum carbide formation is established. The Uc (T0) and Tc (T0) dependencies are linear for the mixture with X = 50%. By hardening the combustion wave, it is revealed that the primary structure formation in the combustion region starts from the selection of submicron grains of nonstoichiometric titanium carbide from the supersaturated titanium melt. In the investigated range of parameter X, synthetic products are single-phase and represent titanium-tantalum carbide. An increase in X results in a decrease in the size and microhardness of (Ti, Ta) C grains and a reduction of the relative density of compact synthetic products. The kinetics of high-temperature oxidation of alloys on the basis of carbide (Ti, Ta) C is studied. Ceramics produced at X = 10% are most heat-resistant.