Complex XRD microstructural studies of hard coatings applied to PVD-deposited TiN films .2. Transition from porous to compact films and microstructural inhomogeneity of the layers

Transition from porous to compact microstructure of magnetron deposited TiN films with increasing energy of incoming particles is associated with the changes of stress and strain. This is studied by conventional powder diffractometry in Bragg-Brentano geometry, by asymmetric diffraction used for stress measurement in the so-called Omega-and psi-goniometer geometries and by the Seemann-Bohlin diffractometry. The changes of lattice parameters and preferred orientation are investigated as well. The results are discussed from several points of view: elasticity theory, lattice defects and heterogeneous microstructure of the films. The heterogeneity seems to be an important reason for specific effects of lattice parameters and X-ray diffraction line broadening anisotropy. The crystallite group method (CGM) is used for the evaluation of stress and crystallite size and reveals the microstructural inhomogeneity. The importance of the orientation of crystallite with respect to the surface for its real structure is further confirmed by the measurement on freestanding film.