Multi-scale strengthened Fe-1Se alloy with antibacterial and antitumor properties for orthopedic applications

Biodegradable Fe-Se alloys are promising for bone-cancer defect repair owing to their significant antitumor properties. However, the inadequate strength and plasticity of as-cast Fe-Se alloys necessitate further research to improve their mechanical properties. In this study, we prepared a high-strength Fe-1Se alloy using ultrahigh-pressure solution treatment. The microstructure of the ultrahigh-pressure solution-treated (UPST) Fe-1Se alloy consisted of body-centered cubic (BCC) α-Fe ferrite, martensite, and FeSe second phase. The solid solubility of Se in the α-Fe matrix of the UPST Fe-1Se alloy significantly increased to 0.53 at. %. Due to the combined strengthening effects of the martensite structure, FeSe nanoprecipitate clusters, and the supersaturated solid solution, the UPST Fe-1Se alloy exhibited a yield strength of 1072.1 ± 5.8 MPa, 4 times that of its solid-solution-treated (SST) counterpart under atmospheric pressure and around 7 times that of the extruded magnesium alloy WE43. Further, the UPST Fe-1Se alloy showed antibacterial capacity against Staphylococcus aureus, biocompatibility with pre-osteoblast MC3T3-E1 cells, and antitumor efficacy against osteosarcoma MG63 cells. In summary, the UPST Fe-1Se alloy has broad prospects in orthopedic applications based on its unique mechanical and biofunctional properties. STATEMENT OF SIGNIFICANCE: This work reports the multiple strengthening mechanisms, corrosion and degradation behaviors, biocompatibility, and biofunctionalities of an ultrahigh-pressure solution-treated Fe-1Se alloy. The microstructure of the alloy consisted of body-centered cubic α-Fe ferrite, martensite, and FeSe second phase. The solid solubility of Se in the α-Fe matrix of the alloy increased to 0.53 at. %. The alloy exhibited a compressive yield strength of ∼1072 MPa. Moreover, the alloy showed antibacterial capacity against S. aureus, biocompatibility in relation to pre-osteoblast MC3T3-E1 cells, and antitumor efficacy against osteosarcoma MG63 cells. In summary, the alloy has broad prospects in orthopedic applications due to its unique mechanical and biofunctional properties.