Microstructures and Mechanical Properties of TiN/CrN Multilayer Films

In order to study the relationship between mechanical properties and microstructure of TiN/CrN multilayer coatings, the TiN, CrN film and three TiN/CrN multilayer films with different periodicities were prepared on monocrystalline silicon by magnetron sputtering. Atomic force microscope and X-ray diffraction were adopted to analyze the surface morphology and phase constitution of the films, respectively. The hardness and indentation plasticity were studied using nanoindenter. Residual stress was measured by a curvature method. The results show that TiN/CrN multilayer films exhibit a mixture of TiN and Cr2N phases, the interface zone between TiN layer and CrN layer becomes small and sharp with the increasing of periodicity. Hardness and indentation plasticity of multilayer films are better than those of monolayer films, and increase as the bilayer period decreases. For multilayer films, the residual stress increases gradually with the increasing of periodicity. From the above observation, it can be concluded that the improvement in mechanical property depends on minor periodicity. The results agree well with Hall-Petch theory.