Study On Microstructure And Properties Of Vacuum Arc Smelting Medical Ti-13Nb-13Zr-xCu Alloy

Featuring excellent mechanical properties,elastic modulus close to human bones,and excellent corrosion resistance,?-type Ti-13Nb-13Zr titanium alloy is widely used as a substitute or repair material for human hard tissue.However,due to its deficiency of antibacterial properties,it may cause secondary injury when it is implanted in human body and affect the use effect and service life of the implant.By alloying an antibacterial element Cu to the Ti-13Nb-13Zr alloy,long-term antibacterial properties can be imparted to titanium alloy.Therefore,in this paper,Ti-13Nb-13Zr-xCu alloy was prepared by combining vacuum arc melting technology and solid solution treatment.The impact of Cu amount(4,7,10,and 13 wt%)in the alloy on the microstructure evolution,mechanical behavior,the anti-corrosion behavior and the effect and mechanism of in vitro antibacterial properties have been studied.The main research results are as follows:With the addition of Cu in Ti-13Nb-13Zr alloy,the microstructure of the alloy was changed.XRD analysis result showed that the Ti-13Nb-13Zr-xCu alloy was mainly composed of?-Ti,?-Ti,Ti₂Cu,CuZr,and Cu₁₀Zr₇phases.As the Cu content increased,?-Tigradually decreased,and?-Tiand precipitated products(Ti₂Cu,CuZr and Cu₁₀Zr₇)increased,that means,the increase of Cu content promoted the formation of?-Tiphase.When 4wt.%Cu was added to the alloy,the precipitated products in the alloy showed oval or irregular strips,which were evenly distributed on the base alloy,but were not connected to each other.As the Cu content increased,the precipitated products gradually grew,widened,and interconnected into one piece;when the Cu content reached 10%,the precipitated product was distributed in a network shape,Cu and Zr elements were mainly distributed on the network structure,and CuZr,Cu₁₀Zr₇and Ti₂Cu was formed.The results of mechanical experiments of Ti-13Nb-13Zr-xCu alloy showed that with increasing Cu content,the yield strength(806?955 MPa)and compressive strength(1132?1481 MPa)of the alloy were greatly improved compared with Ti-13Nb-13Zr alloy.When the Cu content was added to 7wt.%,the yield strength of the alloy(814 MPa)was obviously stronger than other Ti-13Nb-13Zr-xCu alloys.When the Cu content reached 10wt.%,the yield strength and compressive strength both reached higher values,which were 857 MPa and 1360 MPa,respectively.The plasticity of the alloy decreased with the increase of Cu element,and the fracture mode of the alloy changed from plastic fracture to quasi-cleavage fracture.With the increase of Cu content,the elastic modulus of the alloy decreased from the beginning,and then increased.13Nb-13Zr-4Cu?13Nb-13Zr-7Cu and Ti-13Nb-13Zr-10Cu alloys showed lower elastic modulus(64 GPa?59 GPa and 66 GPa,respectively),which was19%?25%and 17%lower than that of Ti-13Nb-13Zr alloy(79 GPa),respectively.The surface hardness of Ti-13Nb-13Zr-xCu alloy was enhanced by solid solution strengthening and precipitation of second phases such as CuZr,Cu₁₀Zr₇and Ti₂Cu to strengthen the alloy matrix(320-331 Hv),where the hardness of 13Nb-13Zr-7Cu alloy was the lowest.It can be seen that Ti-13Nb-13Zr-xCu alloy exhibited excellent mechanical compatibility when the amount of Cu element added was?10wt.%.The Ti-13Nb-13Zr-xCu alloy has been investigated for electrochemical corrosion in artificial body fluid SBF.Electrochemical corrosion results showed that Tion the surface of the alloy mainly existed in the form of TiO₂or Ti₂O₃compounds,Cu existed in the form of Cu O₂or Cu O compounds,and Nb existed in the form of Nb₂O₅compounds.These oxides were present in Ti-13Nb-13Zr-xCu.The oxide film formed on the alloy surface improved the corrosion resistance of the alloy surface.As the Cu content increased,the corrosion current density line of the alloy decreased and then increased,and the resistance value increased and then decreased.That means the corrosion resistance of the alloy increased and then decreased.Ti-13Nb-13Zr-7Cu and Ti-13Nb-13Zr-10Cu alloys showed excellent corrosion resistance.The antibacterial experiment of the Ti-13Nb-13Zr-xCu alloy results showed that with the addition of Cu,the antibacterial effect of the alloy on Staphylococcus aureus and E.coli increased.When the amount of Cu added was?10 wt%,the antibacterial rate of the alloy against the two bacteria was?99%.Ti-13Nb-13Zr-10Cu and Ti-13Nb-13Zr-13Cu exhibited excellent antibacterial properties.In summary,the equivalent precipitation products of Ti₂Cu,CuZr,and Cu₁₀Zr₇in the Ti-13Nb-13Zr-xCu alloy prepared by the combination of vacuum arc melting and solid solution treatment strengthened the alloy matrix to a certain extent,and improved the alloy's corrosion resistance and antibacterial properties.Amongst these alloys,Ti-13Nb-13Zr-10Cu alloy exhibited better mechanical properties,excellent corrosion resistance and antibacterial properties in vitro.The research result will provide theoretical support for promoting its clinical application.