Characterization of cosputtered (TiZrHfY)N x films

Abstract

Medium -entropy TiZrHfY alloy films and corresponding nitride (TiZrHfY)N x films were fabricated through cosputtering. The Ti 0.24 Zr 0.23 Hf 0.27 Y 0.26 film had the form of a hexagonal close -packed (HCP) solid solution with a mixing enthalpy of 9.09 kJ/mol, mixing entropy of 11.50 J/mol & sdot; K (1.38 R), atomic size difference of 7.72 %, and valence electron concentration of 3.73. Moreover, this film had a hardness of 6.0 GPa and an elastic modulus of 106 GPa. (TiZrHfY)N x films with various stoichiometric ratios ( x ) were fabricated by adjusting the reactive gas flow ratio f N2 [N 2 /(N 2 + Ar)] in the range 0.1-0.7. Adding N to the TiZrHfY matrix resulted in a change of phase from an HCP structure to a face -centered cubic phase. The (Ti 0.23 Zr 0.18 Hf 0.24 Y 0.35 )N 0.71 film (with f N2 = 0.2) exhibited the most favorable mechanical properties, having a hardness of 19.1 GPa and an elastic modulus of 244 GPa. Moreover, the film had the highest critical loads ( L C 3 = 46.6 N) among the films analyzed in the scratch test. The anticorrosive properties of the TiZrHfY and (TiZrHfY)N x films were evaluated using potentiodynamic polarization curves, obtained in 3.5 wt% NaCl aqueous solution. High polarization resistance of 1.1 x 10 6 Omega & sdot; cm 2 was obtained for the (Ti 0.23 Zr 0.18 Hf 0.24 Y 0.35 )N 0.71 film, which was 145 times higher than that of the bare SUS420 substrate. The (Ti 0.23 Zr 0.18 Hf 0.24 Y 0.35 )N 0.71 film had the most favorable mechanical and anticorrosive properties of the surveyed (TiZrHfY)N x films.