Synthesis of non-stoichiometric carbides and carbohydrides of Ti and Ti-Nb using self-propagating high-temperature synthesis technique

Abstract

Non-stoichiometric monocarbides are of great interest because they can be used as additives at production of hard alloys. Interestingly, the non-stoichiometric carbides of IV group metals provided with a wide range of homogeneity interact with hydrogen and form ternary compounds, carbohydrides. These compounds attract the researches as the bases for creating new hydrogen containing materials resistant at temperatures above those for known binary hydrides of transition metals. They are promising as materials for biological protection in nuclear energy. In the present work the single-phase non-stoichiometric face-centered cubic (FCC) carbides and hexagonal close packed (HCP) and FCC carbohydrides based on Ti and Ti-Nb were synthesized using Self-propagating High-temperature Synthesis (SHS) method. These syntheses were implemented in one technological stage. The high hydrogen content in the synthesized non-stoichiometric carbohydrides promoted their dispersion down to particle sizes of < 5 µm and even smaller, to the nanoscale crystallite sizes of < 50 nm. The mechanism of formation of non-stoichiometric carbides and carbohydrides in SHS was discussed. Significant advantages of a highly efficient non-energy-intensive SHS method for the synthesis of non-stoichiometric titanium and titanium-niobium carbides and carbohydrides can be of commercial and industry interest.