Epitaxial growth and microstructure of TiN/CrOxNy periodic multilayers

The effect of epitaxial growth on the mechanical properties of periodic multilayer coatings is an important research topic. The focus of this study is the microstructure and mechanical properties of TiN/CrOxNy periodic multilayer thin films consisting of modulated TiN layers. All samples were prepared by magnetron sputtering with varying sputtering powers for the TiN layer, but the CrOxNy layer remained constant. The grazing incidence X-ray reflectometry (GIXRR) and transmission electron microscopy (TEM) results demonstrate the well-defined periodic structure of the thin films, and an accumulating distortion was observed as more layers were added along the growth direction. The results show that the TiN/CrOxNy multilayers possessed a face-centred cubic (fcc) crystal structure and exhibited a (200) preferred orientation of TiN. The thickness of the TiN layers affected the crystalline orientation of the layers. Alternate-orientation epitaxial growth of CrOxNy layers along the TiN layers occurred when N2 was introduced. The introduction of nitrogen and the thickness of the TiN template layers significantly influenced the microstructure and crystallinity of the deposited nanomultilayers. The hardness of the multilayer films was determined by the nanoindentation. The TiN/CrOxNy periodic multilayer prepared from the TiN layer by direct current (DC) sputtering power had the highest nano hardness value, 28.7Gpa.