Grazing angle XRD on ion-nitrided Ti6Al4V components

Surface layers of ion-nitrided Ti5Al4V alloy components were studied by grazing angle X-ray diffraction, using a diffractometer specifically designed for thin films and materials surface characterisation. The study was aimed at the determination as a function of the ion nitriding temperature (700-1000 °C), of the phase composition at different depth under the surface. Present phases were: delta (TiNx, 0.43<x<1.08), epsilon (Ti2N) and alpha (Ti,N) (nitrogen-rich hexagonal titanium). Preliminary results indicate that the outer layer of samples ion-nitrided at 700°C s made of delta-phase, whereas epsilon and alpha phases appear at increasing depth. Differently, the composition layer of samples treated at 1000°C is made of delpa-phase only; an highly oriented alpha-phase is observed below the nitride layer, even if the texture effect tends to disappear at increasing depth, toward the bulk of the metal component, unaffeted by the surface treatment. Ion-nitriding at other temperatures (800-900°C) led to a phase composition intermediate between the two described above.