Optimization of mechanical properties, biocorrosion properties and antibacterial properties of as-cast Ti–Cu alloys

Abstract

Ti-Cu sintered alloys have shown good antibacterial abilities. However, the sintered method (powder metallurgy) is not convenient to produce devices with a complex structure. In this paper, Ti-Cu alloys with 2.0, 3.0 and 4.0 wt.% Cu were prepared in an arc melting furnace and subjected to different heat treatments: solid solution and ageing, to explore the possibility of preparing an antibacterial Ti-Cu alloy by a casting method and to examine the effect of Cu content. Phase identification was conducted on an XRD diffraction meter, and the microstructure was observed by a metallographic microscope, a scanning electron microscope (SEM) with energy disperse spectroscopy (EDS) and transmission electron microscopy (TEM). Microhardness and the compressive property of Ti-Cu alloys were tested, and the corrosion resistance and antibacterial activity were assessed in order to investigate the effect of the Cu content. Results showed that the as-cast Ti-Cu alloys exhibited a very low antibacterial rate against Staphylococcus aureus (S. aureus). Heat treatment improved the antibacterial rate significantly, especially after a solid and ageing treatment (T6). Antibacterial rates as high as 90.33% and 92.57% were observed on Ti-3Cu alloy and Ti-4Cu alloy, respectively. The hardness, the compressive yield strength, the anticorrosion resistance and the antibacterial rate of Ti-Cu alloys increased with an increase of Cu content in all conditions. It was demonstrated that homogeneous distribution and a fine TiCu phase played a very important role in the mechanical property, anticorrosion and antibacterial properties. Furthermore, it should be pointed out that the Cu content should be at least 3 wt.% to obtain good antibacterial properties (>90% antibacterial rate) as well as satisfactory mechanical properties.

Optimization of mechanical properties, biocorrosion properties and antibacterial properties of wrought Ti-3Cu alloy by heat treatment

“…As a kind antibacterial implant material, the Ti-Cu alloys should exhibit strong antibacterial ability, but also possess high mechanical properties, good corrosion resistance for long-term loading bearing application. Previous studies have proven that the Cu content of Ti-Cu alloy must be more than 3 wt% for good antibacterial ability [ 10 , 14 ]. The heat treatment can not only improve the mechanical properties but also affect the antibacterial property by changing the state and distribution of Cu.…”

“…Then, Ti–Cu sintered alloy with 5 wt% or high Cu exhibits a strong and stable antibacterial rate (>99%) against S. aureus and E. coli [ 10 , 11 ]. Recently, ingot metallurgy as well as subsequent metal forming processing has been used to produce antibacterial titanium, such as Ti-6Al-4V-xCu (X = 1, 3, 5 wt%) [ 12 ], Ti-5Cu and Ti-10Cu [ 13 ], and Ti-Cu alloys with 2–4 wt% Cu [ 14 ]. Both Ti-Cu sintered alloy and Ti-Cu ingot alloy show excellent cytocompatibility and have no influence on the cell proliferation and differentiation [ 15 , 16 ].…”

“…It has been reported that the content of Cu and the existing form of Cu element had great influence on the antibacterial properties of Ti-Cu alloy. In order to get good antibacterial rate (>90%), the Cu content in Ti-Cu alloy has to be at least 3 wt% [ 10 , 14 ].…”

“…Souza [ 18 ] found that cooling rate higher than 9 °C/s leds to the formation of the α-Ti and smaller Ti 2 Cu spheres (∼5 nm diameter), and the hardness was improved greatly due to the existence of nanoscale Ti 2 Cu phases. Our previous study also reported that homogeneously dispersed and fine Ti 2 Cu would provide strong strengthening effect, good corrosion resistance and strong antibacterial ability [ 13 , 14 , 19 ]. All these indicate the shape and size of Ti 2 Cu phase significantly influences the antibacterial properties and mechanical properties as well corrosion properties.…”

“…It has shown that Ti-3wt%Cu alloy exhibited comprehensive high antibacterial, high ductility and strength [ 14 ], therefore, Ti-3 wt.% Cu was prepared in this paper by ingot metallurgy followed by forging. It was proposed to obtain good corrosion resistance and mechanical properties of Ti-3Cu alloy by adjusting the existing form of Ti 2 Cu phase without reduction in antibacterial properties.…”