Structural and mechanical properties of AlTiTaZr([sbnd]N) medium entropy films (MEF) obtained by DC magnetron sputtering in dynamic mode

Abstract

New AlTiTaZr medium entropy films (MEFs) are elaborated by using direct current magnetron sputtering of four pure metallic targets. The films are deposited in various argon‑nitrogen gas mixtures on glass, silicon and sapphire positioned in the center and in the targets axis of a rotating substrates holder. Crystallographic structure evolution, as a function of the nitrogen content, is predicted by calculating the phase selection criteria. The theoretical predicted structures are consistent with X-ray diffraction analysis results. Without nitrogen, the films are amorphous, and by increasing the N2 content in the gas mixture, they are single phased faces centered cubic (FCC). A {200} preferential growth of AlTiTaZr(N) films is favored in the targets axis position with increased nitrogen flow rate, whereas those in the center position of substrates holder grow preferentially with {111} planes parallel to the substrates surface.Hardness and Young's modulus are improved with increasing of the nitrogen flow. The highest values were obtained for those in the targets axis position and reach 24.64 GPa and 148.4 GPa for the hardness and the Young modulus respectively. These films were annealed at 600 °C and 900 °C in vacuum and their thermal stability is discussed.