Low elastic modulus and superb antibacterial performance in copper-bearing refractory high-entropy alloys

In the pursuit of next-generation implant materials , reconciling the dual challenges of eliminating bacterial infections and reducing elastic modulus presents a significant hurdle. This feature stems from the trade-off between the low elastic modulus and antibacterial properties in conventional biomedical alloys. Here, we present a novel approach leveraging the exceptional phase stability of refractory high-entropy alloys (RHEAs) to engineer copper-bearing RHEAs with both low elastic modulus and outstanding antibacterial activity. Through (TiZr) 80 (NbTa) 20- x Cu x (at%) RHEAs, we achieve a stable body-centered-cubic matrix with low elastic modulus, consistent with predictions of d -electron alloy design criteria and valence electron concentration theory. Moreover, the introduction of Cu leads to the formation of a Cu-rich phase (CuZr 2 ), significantly enhancing antibacterial efficacy while exerting minimal impacts on elastic modulus. Our optimized (TiZr) 80 (NbTa) 15 Cu 5 RHEA displays a low elastic modulus of 75 GPa, a high antibacterial rate exceeding 90 %, robust mechanical properties , excellent corrosion resistance , and negligible cytotoxicity. The present work not only surmounts the traditional trade-off between the low elastic modulus and antibacterial properties but also provides valuable insights for designing new biomedical-implant alloys. • Cu-bearing RHEAs with low elastic moduli and antibacterial ability are designed. • Osteoblasts co-culturing reveals good biocompatibility of the designed alloys. • The Cu-bearing RHEAs exhibit excellent corrosion resistance . • The influence of phase stability on properties are elaborated.