Design and Development of High-Entropy Alloys with a Tailored Composition and Phase Structure Based on Thermodynamic Parameters and Film Thickness Using a Novel Combinatorial Target

This study presents a novel synthesis route for high-entropyalloys(HEAs) and high-entropy metallic glass (HEMG) using radio frequency(RF) magnetron sputtering and controlling the HEA phase selectionaccording to atomic size difference (& delta;) and film thickness.The preparation of HEAs using sputtering requires either multitargetsor the preparation of a target containing at least five distinct elements.In developing HEA-preparation techniques, the emergence of a novelsputtering target system is promising to prepare a wide range of HEAs.A new HEA-preparation technique is developed to avoid multitargetsand configure the target elements with the required components ina single target system. Because of a customizable target facility,initially, a TiZrNbMoTaCr target emerged with an amorphous phase owingto a high & delta; value of 7.6, which was followed by a solid solution(SS) by lowering the & delta; value to 5 (& LE;6.6). Thus, thissystem was tested for the first time to prepare TiZrNbMoTa HEA andTiZrNbMoTa HEMG via RF magnetron sputtering. Both films were analyzedusing X-ray diffraction (XRD), X-ray photoelectron spectroscopy, fieldemission scanning electron microscopy cross-sectional thickness, andatomic force microscopy (AFM). Furthermore, HEMG showed higher hardness10.3 (& PLUSMN;0.17) GPa, modulus 186 (& PLUSMN;7) GPa, elastic deformation(0.055) and plastic deformation (0.032 GPa), smooth surface, lowercorrosion current density (I (corr)), androbust cell viability compared to CP-Ti and HEA. XRD analysis of thefilm showed SS with a body-centered cubic (BCC) structure with (110)as the preferred orientation. The valence electron concentration [VEC= 4.8 (<6.87)] also confirmed the BCC structure. Furthermore, themorphology of the thin film was analyzed through AFM, revealing asmooth surface for HEMG. Inclusively, the concept of configurationalentropy (& UDelta;S (mix)) is applied and thecrystalline phase is achieved at room temperature, optimizing theprocessing by avoiding further furnace usage.