Achieving superior mechanical properties and biocompatibility in an O-doping TiZrNb medium entropy alloy

The present work aimed to develop a novel medium entropy alloy (MEA) with superior mechanical properties and biocompatibility for the metallic-bioimplant application. A series of (TiZrNb0.7)100-xOx (x = 0, 0.5, 0.75 at. %) MEAs were carefully designed and prepared. The microstructure, mechanical properties, corrosion resistance, and biocompatibility were investigated in detail. Single-phase body-centered cubic (BCC) structural (TiZrNb0.7)100-xOx MEAs consisted of as-cast dendritic morphology. Interestingly, the yield strength and ductility of (TiZrNb0.7)100-xOx MEAs were improved simultaneously with their O concentration. The (TiZrNb0.7)99.25O0.75 MEA had optimal mechanical properties, exhibiting a yield strength of 911 ± 11 MPa, a fracture elongation of 16.1 ± 0.7%, and an elastic modulus of 70.5 ± 1.2 GPa. According to the potentiodynamic polarization and cell culture experiment, the (TiZrNb0.7)99.25O0.75 MEA exhibited superior corrosion resistance and biocompatibility, equivalent to the commercially pure titanium (CP-Ti). These findings provide a paradigm for achieving outstanding comprehensive properties in MEA via O doping.