Features of (Ti, Me)C solid solution formation

Abstract

The structure and phase composition of the products of combined carbothermal reduction of titanium and niobium (tantalum) oxides with an excess of carbon are studied. It is established that formation of solid solutions (Ti, Nb)C and (Ti, Ta)C occurs through successive stages of synthesis of the individual carbides followed by dissolution of TiC in NbC (TaC). Excess of carbon provides high dispersion of the reduction products and their purity with respect to oxygen. Features of solid solution (Ti, Nb)C formation with interaction of niobium oxide and titanium carbide with an excess of carbon (12 mass%) are studied. Use of fine-grained titanium carbide, pure with respect to oxygen, with excess carbon made it possible to reduce by 300°C the temperature for forming homogenous solid solution and to obtain powder with a particle size of less than 8 μm without grinding.

Physical Properties of the NbC Carbide

“…There are several versions of the C-Nb phase diagram published in the literature, both from experimental information [15][16][17][18], as well as from thermodynamic assessments using the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) protocol [19][20][21][22][23][24][25]. Some features of the C-Nb system are not completely understood, especially the order-disorder transformations present in this system.…”