On the bio-corrosion and biocompatibility of TiTaNb medium entropy alloy films

Some high or medium entropy alloys (HEAs and MEAs) have been demonstrated to exhibit great mechanical and bio-corrosion properties to meet the demands as bio-implant materials. However, the difference in Young's modulus between these alloys and human bone would induce stress shielding effects. Therefore, HEA or MEA coating films appear to be potential materials since these films can be coated on appropriate implant devices as surface modification. This study employs sputtering to produce equimolar TiTaNb MEA film and a titaniumbased Ti-10Ta-6Nb film in order to compare their mechanical and bio-corrosion properties. The results indicate that the TiTaNb MEA films have higher hardness, higher wear resistance, greater biocompatibility and superior bio-corrosion resistance, likely to be a high potential bio-implant coating materials. The underlying related chemical reactions and mechanisms are also explored and discussed.