Effects of copper and zinc content on phase formation and functional properties of novel titanium zirconium biomedical alloys

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Achieving a balanced combination of corrosion resistance, wear performance, and biological response in titanium-based biomaterials remains a significant challenge because enhancement in one property does not necessarily benefit the others. This study introduces a novel Ti-Zr-Cu-Zn quaternary alloy system and investigates the coupled effects of addition of Cu and Zn to achieve optimal properties. Unlike previous studies that primarily aimed at individual alloying additions, the present study is first of its kind aimed at synergistic optimization of electrochemical, tribological and biological responses. A series of alloy compositions were designed using the Taguchi method by systematically varying the composition of Cu and Zn, and synthesized using the powder metallurgy technique. The alloys were initially characterised through phase and microstructural analysis followed by evaluation of corrosion, wear and in-vitro cell viability. The results revealed significant changes in phase and microstructural features, showing the formation of α-(Ti, Zr), β-(Ti, Zr), Ti₂Cu, and Ti₂Zn phases. While Cu promoted the formation of β-(Ti, Zr) and Ti₂Cu phases, Zn exhibited a non-linear effect with 15 wt% Zn giving the maximum β-(Ti, Zr) and Ti 2 Zn fractions. These variations were accompanied by pronounced changes in microstructures and β-phase area fractions. Among all the compositions studied, Ti–30Zr–6Cu–15Zn exhibited the optimal performance with lowest corrosion and wear rates, and highest cell viability. Statistical analysis using two way ANOVA and signal to noise ratio calculations proved the significant roles of Cu and Zn in enhancing the functional performance of the alloys.