Microstructure, mechanical properties and tribological behavior of (TiZrHfNbTa)Nx high entropy films deposited by magnetron sputtering

High entropy nitride (HEN) films of (TiZrHfNbTa)Nx were deposited by reactive DC magnetron sputtering, choosing 304 stainless steel and silicon wafers as the experimental substrates. The influence of nitrogen flow rate R-N: N-2/(N-2+Ar) on the microstructure and properties of HEN films was investigated. The results showed that HEN films exhibit granular surface morphologies and internal characteristics of amorphous embedded FCC crystals, exhibiting a structure of amorphous at the lower R-N (0, 2 %) and transforming to FCC crystals with preferred (111) orientation as R-N increasing (6.5%-26 %), with the decrease of crystallinity and the alteration of preferred orientation from (111) to (200) at the further increase of R-N at 40 %. The introduction of nitrogen led to significant improvements of film hardness (>23 GPa) and modulus (>270 GPa). When R-N = 13 %, the hardness is up to 30.7 GPa, and the modulus is 340 GPa at R-N = 6.5 %. The as-deposited films exhibited excellent wear resistance, and the wear rate (6.65x10(-6)mm(3)/Nm) was the lowest when R-N = 2 %.