MAGNETRON SPUTTERING DEPOSITION OF HIGH ENTROPY NITRIDES FROM ChRomium-HaFnium-MOlybdenum-TAntalum-Wolfram SYSTEM

Abstract

High entropy alloys (HEAs) are multicomponent materials with at least five elements close to the equiatomic ratio. The multielement composition leads to many effects that stabilize solid solution phases instead of intermetallic compounds. It results in promising mechanical properties, high thermal stability, good corrosion resistance, etc. After the discovery of HEAs in 2004, the concept only concerned metallic materials. Later, the idea was extended to high entropy ceramics (carbides, nitrides, oxides). In this study, the high entropy nitrides (HENs) from the Cr-Hf-Mo-Ta-W system were deposited by magnetron sputtering from elemental segmented targets. Two series of samples were deposited under different nitrogen flow from 0 sccm to 20 sccm at ambient temperature and 700 °C. The coatings deposited at low nitrogen flow consist predominantly of metallic and amorphous phases. At higher nitrogen flow (above 10 sccm), the coatings mainly consist of multielement facecentered cubic nitride with nanometric grain size, which lattice parameter increases with increasing nitrogen content. The chemical composition of films varies as a function of nitrogen flow and temperature. With increasing nitrogen flow and temperature, the deposition rate decreases from 67 nm min -1 at ambient temperature with no nitrogen to 38 nm min -1 at 700 °C under 20 sccm nitrogen flow. The coatings revealed high hardness up to 26.6 GPa and Young's modulus up to 531 GPa.