Effect of nitrogen content and substrate bias on mechanical and corrosion properties of high-entropy films (AlCrSiTiZr)100-xNx

High-entropy alloy and nitride films of (AlCrSiTiZr)(100 - x)N-x containing large Zr atoms and small Si atoms were deposited on 6061 aluminum alloy and mild steel substrates by DC reactive magnetron sputtering at various nitrogen flow ratio (R-N). The composition, crystalline structure, and film morphology were analyzed by electron probe X-ray microanalyzer (EPMA). X-ray diffractometer (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM), respectively. Also, their hardness and elastic modulus were studied by nanoindentation. The corrosion behavior was studied by anodic polarization analysis in 0.1 M H2SO4 aqueous solution at room temperature. The properties of films deposited under substrate bias application were also studied. The tendency of the present composition to form amorphous or low-crystallinity structure is high because of its large difference in atomic size. Films demonstrate pure amorphous structures even as the nitrogen content reaches as high as 22.4 at.%. All coatings can provide better corrosion resistance on both 6061 aluminum alloy and mild steel substrates. Under condition of no applied substrate bias, films of (AlCrSiTiZr)(100 - x)N-x deposited at R-N = 30% give the best corrosion resistance. Substrate bias of - 100 V effectively improves the corrosion resistance of the amorphous film of (AlCrSiTiZr)(100 - x)N-x (R-N= 5%). The factors that might influence the corrosion resistance were also discussed. (c) 2012 Elsevier B.V. All rights reserved.