On the microstructure, electrochemical properties, biocompatibility, and cytotoxicity of TiAlFeCoX (X=Ni, Cu) high-entropy alloy thin films, deposited by DC magnetron sputtering

Abstract

This study investigates the microstructure, corrosion behavior, biocompatibility, and cytotoxicity of TiAlFeCoNi and TiAlFeCoCu high-entropy alloy thin films, deposited on AISI 316L stainless steel by direct current magnetron sputtering. Grazing incidence X-ray diffraction (GIXRD), electron microscope, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) were used to investigate microstructural and electrochemical properties of deposited thin films. GIXRD and FE-SEM results showed that elements are homogenously distributed in the coating layers and that the coatings have amorphous structure. The potentiodynamic polarization results suggests that both compositions have improved the corrosion resistance of the base alloy. In vitro biomineralization test showed that both compositions are indeed bioactive, given that crystals of hydroxyapatite were formed on both coatings after 7 days of immersion in the simulated body fluid (SBF), as opposed to the stainless-steel substrate which did not show any noticeable bioactivity. Cytotoxicity assessments showed that the TiAlFeCoNi coating has comparatively much higher cell viability. Overall, TiAlFeCoNi appears to be a very promising coating for biomedical applications.