Phase Transformations in Ti₃Sn and Ti₂Sn Intermetallics During Hydrogenation

The sequence of phase transformations in Ti₃Sn and Ti₂Sn intermetallics during their interaction with hydrogen is studied. The mechanism whereby Ti₃Sn hydride phases form is clarified. It is shown that Ti₃Sn reacts with hydrogen at 373–1173 K through hydrogen ordering of the initial intermetallic structure, subsequent amorphization, and restructuring during the formation of hydride phases in the following sequence: hcp Ti₃Sn → diamond Ti₃SnH_0.8 → hcp Ti₃SnH_0.8–0.9 → fcc Ti₃SnH_0.9–1.0 → bcc Ti₃SnH_1+x. A new hydride phase, Ti₃SnH_1+x (bcc, a = 0.538 nm), with high hydrogen capacity compared to the known fcc Ti₃SnH hydride, which decomposes when heated to 1073 K, has been found. Destructive hydrogenation of Ti₃Sn at 298–1173 K and hydrogen pressures of 1.0–6.0 MPa is not revealed. It is found that intermetallic Ti₂Sn reacts with hydrogen through destructive hydrogenation to form a solution of hydrogen in β-titanium, hydride of a face-centered tetragonal solid solution of tin in titanium, and intermetallic Ti₅Sn₃.