The microstructure and mechanical properties of TiNNi nanocomposite thin films

The effect of varying substrate bias and temperature on the microstructure and properties of TiNNi nanocomposite thin films, fabricated using a filtered cathodic vacuum arc, was investigated. Films deposited at room temperature with no applied bias had low surface roughness and exhibited fine microstructure. An increase in bias or temperature resulted in significant changes in microstructure, including an increase in the crystallinity of the Ni phase and an increase in TiN and Ni crystallite sizes. At a substrate bias of − 500 V, separation of the TiN and Ni phases was observed resulting from the high-energy ion bombardment. The intrinsic stress and hardness of the films were found to decrease with increasing Ni crystallite size. The TiNNi nanocomposite films were found to exhibit lower hardness than a TiN film deposited using similar conditions and were more ductile due to the presence of metallic Ni. The film deposited at room temperature and low bias was found to be highly elastic, exhibit reasonable hardness (~ 18 GPa) and low intrinsic stress. This combination of properties has the potential for exploitation in a range of tribological applications.