Biocompatible as-cast and homogenized TiNbTaZrMoV high entropy alloys: mechanical properties, corrosion resistance and in vitro studies

Abstract

Commercial 316L SS, CoCrMo, and Ti6Al4V alloys have been widely used as implant materials for biomedical applications. However, the inadequate wear resistance and the released metal ions could result in inflammation, cytotoxicity, and shorten the lifespan of surgical implants. To extend the service life and durability of metallic biomaterials, the TiNbTaZrMoV HEA was developed by integrating biocompatibility characteristics with the unique properties of high-entropy alloys (HEAs). Both as-cast TiNbTaZrMo and TiNbTaZrMoV HEAs consisted of dual BCC phases in the dendritic structure: the dendrite region was enriched with Ta, Mo, and Nb, while Zr, Ti, and V were concentrated in the interdendrite region. The homogenized TiNbTaZrMoV HEA possessed a single BCC phase with a homogeneous component distribution. Moreover, the wear resistance of the homogenized TiNbTaZrMoV HEA was superior to the as-cast TiNbTaZrMo and TiNbTaZrMoV HEAs. In terms of electrochemical behaviors, the homogenized TiNbTaZrMoV HEA exhibited superior corrosion resistance compared to the other commercial metallic biomaterials in phosphate-buffered saline solution at 37 °C. The in vitro biocompatibility evaluation revealed that the homogenized TiNbTaZrMoV HEA could support the attachment and proliferation of the MC3T3-E1 cells, presenting good biocompatibility comparable to the Ti6Al4V alloy. This study demonstrated the feasibility of the homogenized TiNbTaZrMoV HEA for orthopedic bioimplant applications.