Destructive Hydrogenation and Recombination of α2-Ti3Al Alloy: Production of Solid Nanocomposites and Coatings with Improved Properties. I.Mechanism of Destructive Hydrogenation of Ti3Al


I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2010, #07/08


It is shown that α2-Ti3Al alloy and hydrogen interact at 298–1533 K in accordance with the destructive hydrogenation reaction whose products are titanium hydride and intermetallic compounds rich in aluminum. The structure phase mechanism of α2-Ti3Al destructive hydrogenation is as follows. Hydrogen dissolves in Ti3Al, thus leading to disordering of its crystalline structure. Then hydrogen interacts with titanium, but not with the disordered alloy, according to the following scheme: α-Ti (hcp) → α-TiHx (hcp) → β-TiHy(bcc) → TiH1.9(fcc) → TiH2(bct). The intermetallic compounds rich in aluminum show up when new stoichiometric concentrations of titanium and aluminum form in accordance with Ti–Al phase diagram. Solid composites with nanosized components result from the destructive hydrogenation of Ti3A at 973 K for 1 and 4 h. Their phase compositions are Ti3Al–(α-TiH–Ti3–xAl) and ((α-Ti–Hx)–(β-Ti-Hy)–TiH1.9(fcc)–TiH2(bct))–(Ti3Al–TiAl–TiAl2), respectively.