Structure, morphology and nanoindentation behavior of multilayered TiN/TaN coatings

TiN/TaN coatings, consisting of alternating nanometer-scale TiN and TaN layers, were deposited using a magnetron sputtering system. The structure, morphology and hardness were assessed using X-ray diffraction, atomic force microscopy (AFM) and nanoindentation, respectively. The results showed that the TiN/TaN coatings exhibited good modulation periods and a sharp interface between TiN and TaN layers and had cubic structure. The hardness (H) and elastic modulus (E) of TiN and multilayered TiN/TaN films on Si substrate were evaluated by hardness-depth and elastic modulus-depth curves measured by a depth-sensing nanoindentation technique. And the yield strength was calculated using a relationship between the H, E and Y. The hardness characteristics of thin-film coated composites were predicted using the plastic-zone volume-law of mixture theory. The behavior of composite hardness is well predicted over the total indentation depth using the present analysis, even though there are large deviations between the analysis and the experimental results for TiN/TaN/Si systems.