Structure and properties of nanocomposite Nb–Al–N films

Nanocomposite Nb–Al–N films prepared by magnetron sputtering have been studied. It has been found that, in the films, there are two stable crystalline structural states, namely, NbN$_z$ and B1-Nb$_{1-x}$Al$_x$N$_y$O$_{1-y}$, and an amorphous-like component related to aluminum oxynitride upon reactive magnetron sputtering. It has been established that the substructure characteristics are sensitive to the current supplied to an Al target and are related to the Knoop nanohardness and hardness, which change in the ranges of 29–33.5 and 46–48 GPa, respectively. Ab initio calculations for the NbN$_z$ and Nb$_2$AlN phases and NbN/AlN heterostructures have been performed to interpret the obtained results for the first time.