On orientation relationship of the Ti5Si3 precipitates in a TiAl alloy

The orientation relationship (OR) and interface structure between ζ-Ti5Si3 precipitates and γ-TiAl phase in a Ti–Al based alloy composed of γ-TiAl and α2-Ti3Al lamellae have been investigated using transmission electron microscopy. Various orientation relationships defined by a pair of parallel directions and planes are discussed with the method of basic vector transformation matrix in the reciprocal space from γ-TiAl to ζ-Ti5Si3 precipitate phase and two new kinds of orientation relationships between ζ-Ti5Si3 and γ-TiAl phases have been found. Periodical interface fringes at γ-TiAl/ζ-Ti5Si3 interface are analyzed according to the Moiré fringes and interface misfit dislocations.