Enhanced mechanical, bio-corrosion, and antibacterial properties of Ti-Cu alloy by forming a gradient nanostructured surface layer

Abstract

To improve the comprehensive performance of Ti-Cu alloy, a gradient nanostructured surface (GNS) layer was formed on Ti-Cu alloy by surface ultrasonic rolling treatment (SURT). The surface features, mechanical properties, corrosion resistance, antibacterial properties, and cell compatibility of Ti-Cu alloy before and after SURT were systematically investigated. The surface of GNS Ti-Cu is mainly composed of Cu2O and TiO2, as well as a small amount of Ti, and shows improved wettability. The thickness of the GNS layer is ~200 μm and the average grain size in the topmost layer is ~4 nm. The mechanical properties (microhardness, strength-ductility synergy, and wear resistance) and corrosion resistance are enhanced due to the existence of GNS layer on Ti-Cu alloy. The antibacterial tests demonstrated that GNS Ti-Cu obtains excellent antibacterial ability against Staphylococcus aureus and Escherichia coli, the antibacterial mechanism can be attributed to the accelerated Cu2+ leaching and the contact sterilization of Cu2O. Finally, biocompatibility experiments via MC3T3-E1 cells indicated that GNS Ti-Cu possesses improved cell spread ability and osteoblastic differentiation, showing satisfied biocompatibility. This work demonstrated that Ti-Cu alloy with superior comprehensive performance can be achieved by forming a GNS layer, which has great application potential in the field of metallic biomaterial.