Control of γ lamella precipitation in Ti–39 at.% Al single crystals by nanogroove-induced dislocation bands

摘要: Abstract We attempted to control γ lamellae precipitation in Ti–39 at.% Al single crystals by nanogrooving process (NGP) intending introduce periodic dislocation bands as preferential nucleation sites of γ-TiAl precipitates. In NGP, grooves were formed along the trace (0 0 0 1) basal plane on surfaces crystal α2-phase supersaturated with Al-atoms nano-scale plastic deformation using diamond knives edge angle 60°. The widths ranged from 180 nm 1860 nm for load per knife-edge length range 0.3 N/mm 8.3 N/mm. Beneath grooves, consisting both dislocations and non-basal formed. After aging at 1073 K 1 × 104 s, pairs found form only beneath depths greater than 30 μm, meaning that location could be controlled NGP. Increasing temperature 1173 K provided even control, arrays lamella bundles exhibiting a periodicity identical nanogrooves, near surface no un-deformed regions. No concentration gradient was within individual lamellae, which had near-equilibrium concentration; thinner tended have slightly lower concentration. These results indicate can effectively introducing opens new avenue manufacturing near- or sub-wavelength grating structures ultra-high aspect ratios through selective dissolution these lamellae.