CNx/TiAlN multilayered coatings with different nanoscale modulation periods and ratio of CNx within each period were prepared by ion-beam-assisted deposition at room temperature. Auger electron spectroscopy (AES), x-ray diffraction (XRD), and nanoindenter and a profiler were used to characterize the microstructure and mechanical properties of the coatings. The low-angle XRD pattern and AES indicated a well-defined multilayered structure of the coating. Although monolithic CNx and TiAlN coatings formed amorphous and nanocrystalline structures, respectively, the CNx/TiAlN multilayers exhibited coherent epitaxial growth due to the mutual growth-promoting effect at small CNx layer thickness (< 0.6 nm). At modulation period Lambda = 2.83 nm and CNx thickness of 10% within each period, the multilayers exhibited strong TiAlN (111) and weak AlN (111) textures and showed the highest hardness (32 GPa), elastic modulus (409 GPa), and critical fracture load (65.7 mN). (C) 2008 American Vacuum Society.