Face-centered tetragonal titanium hydrides in fine-grained commercial pure (grade 2) titanium

Face-centered tetragonal (fct) titanium hydride was observed by transmission electron microscopy in commercially pure (CP, grade 2) fine-grained (FG) titanium produced by severe plastic deformation (SPD) and annealing. This γ-fct titanium hydride has a c/a ratio of 1.08. It was found that the γ-fct hydride possesses inherent orientation relationships with the FG hexagonal close-packed (hcp) α-Ti matrix, namely (110)γ∥(101¯0)α, [001]γ∥[0001]α, [1¯14]γ∥[1¯21¯6]α and [1¯12]γ∥[12¯13¯]α. The fct titanium hydride plates within hcp matrix have the thickness of 10–150nm and length of 50nm–3μm while the matrix grains have the size of 50nm to 3μm. The fct titanium hydride was found to be very scarce in this Ti and the relationship between the length of γ-fct hydride and grain size of the hcp matrix has also been discussed. [Display omitted] •We observed fct titanium hydrides in severely deformed and annealed FG Ti.•This γ-fct titanium hydride has a c/a ratio of 1.08.•The γ-fct hydride has inherent orientation relationships with the FG hcp Ti matrix.•The fct hydride plates were found to be very scarce in this Ti.•Length of hydride plate cannot be larger than grain size of the hcp matrix.