Deposition of high entropy alloy sub-surface films on metal substrates via DC magnetron sputtering with a CoCrFeMnNi target

High entropy alloys and high entropy alloy films (HEFs) are gaining increasing attention in the research community due to their superior mechanical properties. CoCrFeMnNi is one of the most investigated of these alloys in the literature; however, CoCrFeMnNi HEFs have not yet been extensively reported. To improve our understanding of the processes occurring during fabrication of CoCrFeMnNi HEFs, here, DC magnetron sputtering using a CoCrFeMnNi equimolar target is used to deposit HEFs on glass substrates, A5052 aluminum sheets, and S45C steel sheets. The resulting HEFs are observed to be embedded as sub-surface bands, less than a micrometer under the substrate surface. This is attributed to implantation of the HEF elements into the base material due to the high deposition energy of sputtering. Another possibility is that substrate elements migrate to the surface in an Ar plasma-assisted process. The HEF crystallite size on glass substrates was determined by x-ray diffraction to be several nanometers, meaning that high hardness is expected in HEFs produced by DC magnetron sputtering.