Structural and Phase Transformations and Interaction of Ti₂Co and TiCo Intermetallics with Hydrogen and Synthesis of Nondestructive Nanostructured Titanium Hydride Composites

Abstract

The paper examines the sequence of structural and phase transformations and the rate of Ti₂Co and TiCo interaction with hydrogen. Destructive hydrogenation of Ti₂Co is used to produce nondestructive nanostructured composites based on titanium hydride. Thermodynamic analysis has shown that Ti₂Co and TiCo destructive hydrogenation in the temperature range 298–973 K is thermodynamically favored. In the temperature range 773–973 K, Ti₂Co interacts with hydrogen by destructive hydrogenation reaction, in which hydrogen is dissolved in the intermetallic compound, titanium is selectively hydrogenated to cubic TiH_1,9, and titanium-depleted TiCo and TiCo₂ intermetallics are successively formed in accordance with the Ti–Co phase diagram. The rate of Ti₂Co destructive hydrogenation is proportional to temperature, hydrogen pressure, and surface area of the starting samples. Compound TiCo is hydrogenated to form a solution of hydrogen in Ti_1+yCo, intermetallic TiCo₂, and a solution of hydrogen in β-titanium. Nondestructive composites with nanostructured components are synthesized by Ti₂Co destructive hydrogenation.