Diamond coatings have been deposited in a microwave plasma from CH4-H-2 and CO-H-2 mixtures, with the aim of improving the wear resistance of titanium alloys. In-depth distribution profiles of crystalline phases formed during the diamond films growth are measured here using Grazing Incidence X-ray Diffraction (GIXD), in correlation with Scanning Electron Microscopy (SEM) coupled with EDX analysis. The GIXD method is particularly well adapted to study surface modifications or depositions of polycrystalline materials. Especially in this case, the formation of different intermediate carbonaceous layers are evidenced in terms of microstructure, from the diamond films to the titanium alloy substrate. In addition, crystalline parameters, microstrain rates and coherent domain size evolutions of different alpha and beta-Ti alloy solid solutions, titanium carbide and diamond phases have been studied with respect to grow th kinetics and deposition temperature, at 600 degrees C and 850 degrees C.