Structure, phase composition and hardness of TiZrAlN films with different Al content

Quaternary TiZrAlN films were grown at T_s=600°C by reactive magnetron sputtering in Ar+N₂ plasma discharge from elemental targets. Deposition occurred at the constant power of Ti and Zr targets, while changing the Al power and adjusting the N₂ flow rate, resulting in stoichiometric nitride films (N concentration ~ 50 at.%) with Al content up to 37 at.% and fixed Zr:Ti ratio of 1:1. It is shown that single-phase, cubic (Ti,Zr)_1-xAl_xN solid solutions are stabilized upon incorporation of Al. The lattice parameter of Al-containing films linearly decreases with the increase in Al concentration. For these films the maximum hardness (25 GPa) is achieved at Al content of 19 at.%. (authors)