X-ray diffraction analysis of the anisotropic nature of the structural imperfections in a sputter-deposited TiO2/Ti3Al bilayer

X-ray diffraction analysis was employed for the investigation of the structural imperfections of a sputter deposited TiO2/Ti3Al bilayer: The spatial distribution of crystallite size, microstrain and crystal orientation, as well as the strain-free lattice parameters, residual stresses and the Debye–Waller factor, were determined. The TiO2 sublayer is largely amorphous. The Ti3Al sublayer is polycrystalline and exhibits a pronouncedly anisotropic microstructure: It consists of columnar, needle-shaped crystallites with the crystal lattice c-axis as needle axis. The microstrain of the Ti3Al-layer increases upon changing the viewing (diffraction vector) direction from vertical to parallel to the layer surface. The Ti3Al layer is subjected to a large compressive macrostress parallel to the surface. The Debye–Waller parameter as determined for the Ti3Al sublayer is larger than that of a reference Ti3Al specimen. The investigations were complemented by transmission electron microscopy and energy-dispersive X-ray spectroscopy.