Phase Transformations in Ti₃Sn and Ti₂Sn Intermetallics during Hydrogenation

Abstract

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, its amorphization, and consistent restructuring during the formation of hydride phases as follows: 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 with 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 solid solution of tin in titanium with face-centered tetragonal structure and intermetallic Ti₅Sn₃.