Bio-corrosion behavior and in vitro biocompatibility of equimolar TiZrHfNbTa high-entropy alloy

Abstract

Ti20Zr20Hf20Nb20Ta20 high-entropy alloy (TiZrHfNbTa HEA) is considered to be attractive for biomedical applications due to its good mechanical properties and composition that composed of biocompatible elements. In the present study, the bio-corrosion behavior in a simulated physiological environment and in vitro biocompatibility of the TiZrHfNbTa HEA were investigated in comparison with those of the Ti-6Al-4V alloy. It was found that the TiZrHfNbTa HEA exhibited as good bio-corrosion resistance as that of the Ti-6Al-4V alloy in the Hank's solution at 310 K, as revealed by the spontaneously-passivating behavior with a low passive current density of about 10−2 A/m2, a low corrosion rate in the order of 10−4 mm/year, and high electrochemical impedance of the HEA. X-ray photoelectron spectroscopy (XPS) analysis of the alloy surface suggested that the formation of the passive film composed of TiO2, ZrO2, HfO2, Nb2O5, and Ta2O5 is responsible for the high bio-corrosion resistance of the HEA. The good adhesion, viability and proliferation behaviors of MC3T3-E1 pre-osteoblasts on the TiZrHfNbTa HEA indicated its good in vitro biocompatibility. The combination of the good bio-corrosion resistance and in vitro biocompatibility demonstrates the potential of the TiZrHfNbTa HEA for biomedical applications.