Development of Ti-Nb-Mo-Zr Alloys with Low Modulus and Excellent Plasticity for Biomedical Applications

Area of Science:

• Materials Science
• Biomedical Engineering
• Metallurgy

Background:

• Metastable beta titanium alloys offer low elastic modulus and high plasticity, ideal for biomedical stents.
• Zirconium (Zr) is investigated for its role in optimizing beta titanium alloy properties.

Purpose of the Study:

• To investigate the effect of zirconium content on the stability, microstructure, mechanical properties, and deformation mechanisms of Ti-25Nb-2Mo alloys.
• To develop advanced titanium alloys for biomedical stent applications.

Main Methods:

• Design of Ti-25Nb-2Mo-xZr (x = 0, 3, 9, 12 wt%) alloys based on d-electron theory.
• Systematic investigation of microstructure, mechanical properties, and deformation mechanisms using various analytical techniques.
• Evaluation of elastic modulus and tensile plasticity.

Main Results:

• Increasing Zr content significantly enhanced beta phase stability.
• Suppressed formation of high modulus alpha'' and omega phases, leading to reduced elastic modulus.
• Deformation mechanisms shifted from dislocation slip to martensitic reorientation, stress-induced martensite transformation (SIMT), and twinning, enhancing plasticity.
• Ti-25Nb-2Mo-12Zr alloy achieved a low elastic modulus (56.3 GPa) and high elongation to failure (48.2%).

Conclusions:

• Zirconium addition is crucial for tailoring beta titanium alloys for biomedical applications.
• The Ti-25Nb-2Mo-12Zr alloy demonstrates significant potential for biomedical stents due to its superior combination of low elastic modulus and high plasticity.