Bio-tribological Characteristics of 3D-Printed Ti–Ta–Nb–Mo–Zr High Entropy Alloy in Human Body Emulating Biofluids for Implant Applications

This paper presents findings on corrosion and tribo-corrosion characteristics in human body emulating biofluids of 7.4 pH value at 37 °C, dry fretting wear, and abrasion resistance of equiatomic Ti–Ta–Nb–Mo–Zr high entropy alloy (HEA) developed by μ-plasma-based 3D-printing process. Physiological saline, phosphate buffered saline (PBS) solution, and 1% fetal bovine serum mixed with the PBS solution were used as the human body emulating biofluids to study corrosion and tribo-corrosion characteristics of the developed HEA. Minor abrasive wear and material ploughing in dry fretting wear zone are observed occurring due to the formation of loose wear debris and large-scale material displacement, respectively. The presence of biofluids significantly reduced coefficient of friction, average depth of worn scar, specific wear rate, open-circuit potential values, corrosion potential, and corrosion current density. Ti–Ta–Nb–Mo–Zr HEA showed better corrosion and tribo-corrosion resistance than Ti–22Nb, Ti–22Nb–6Zr, Ti–12Mo–5Ta, and Ti–20Nb–10Zr–5Ta alloys due to the formation of strong passive layers of oxides of its constituents, i.e., TiO2, Ta2O5, Nb2O5, NbO2, and ZrO2. It has higher abrasion resistance at higher applied load without much change in coefficient friction imparting it better resistance to wear and tear. Findings of this study make Ti–Ta–Nb–Mo–Zr HEA as preferable orthopedic implant material than the presently used materials. Graphical Abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.