Phase Transformations in Ti₂Cu under Destructive Dehydrogenation and Recombination

Abstract

The thermodynamic possibility and conditions of Ti₂Cu hydrogenation and recombination are assessed. The mechanism of Ti₂Cu interaction with hydrogen between 293 and 973 K at hydrogen pressure of 1.0 MPa is studied. The interaction of Ti₂Cu with hydrogen is possible in the destructive hydrogenation region over a wide temperature range. It is shown by x-ray diffraction that the destructive hydrogenation products are titanium dihydride and copper-rich intermetallic phases and copper depending on the reaction conditions. According to the established mechanism of Ti₂Cu destructive hydrogenation, hydrogen selectively interacts with titanium, which leaves Ti₂Cu composition, as follows: β-TiH_y(bct-bcc) → TiH_1,92 (fcc). The initial Ti₂Cu composition is recombined from its destructive hydrogenation products (titanium dihydride and copper) in vacuum and hydrogen atmosphere. The minimal temperature of Ti₂Cu vacuum recombination is established to be 1050 K and to support complete TiH₂ decomposition. The recombination of Ti₂Cu in hydrogen can take place at temperatures over 907 K.