HRTEM interfacial analysis on superhard TiAlN/Mo multilayers

In this article, we focus on the study of multiple interfaces from nanocomposite TiAlN/Mo multilayers that were fabricated by reactive magnetron sputtering, with modulation periods below 20 nm. The structural disorder at the interfaces was probed by X-ray diffraction (XRD), both in the low and high angle regions, while the interface morphology was studied by high-resolution transmission electron microscopy (HRTEM). Particular attention has been directed to the evolution of the interfacial disorder with the bias voltage. For particular conditions, these structures can be prepared with relatively planar interfaces, revealing layer-by-layer growth and withholding hardness values up to 60 GPa. For modulation periods below 3 nm the interdiffusion acts a major role in the chemical modulation degradation and subsequent hardness decrease. A correlation between the evolution of roughness and hardness will be given, based on the calculations and fits of experimental XRD patterns.