The Mechanical and Electrochemical Properties of TiNbZr-based Alloys
Student thesis: Doctoral Thesis
Related Research Unit(s)
Ti-14Nb-18Zr (at%)-xM (M: Cu, Ag, or Mg TNZ-Cu, TNZ-Ag, or TNZ-Mg) films with nanocrystalline and/ or amorphous structures were deposited by magnetron sputtering. The structure, mechanical and electrochemical properties of the above films were systematically characterized to probe their prospects in biomedical applications. The results showed an extremely asymmetrical performance between tensile and compression tests for nanocrystalline TNZ-3.5wt%Cu, while it is nearly symmetrical for that of TNZ-5wt%Ag and TNZ-5wt%Mg. The in-situ TEM tensile test showed that nanocrystalline TNZ-3.5wt%Cu was mainly deformed by the rotation of grains in it, and nearly no dislocations or twins could be observed. However, for TNZ-5wt%Ag and TNZ-5wt%Mg, grain rotation, dislocations, stacking faults, and twins can also be observed. This might be the underlying reason for the different mechanical behaviors between TNZ-Cu and the latter two alloys. Compressive strength reached over 3 GPa and 1.5 GPa for TNZ-Cu and TNZ-Ag, respectively, with plasticity of over 15% for both. The low elastic modulus was about 60 GPa. For the TNZ-5wt%Mg alloy, both the compressive and tensile strengths reached 2 GPa with a strain of about 20%. The initial elastic modulus of TNZ-Mg is about 69 GPa, while the depleting of Mg in aggressive solutions can further lower the elastic modulus of this alloy. The great mechanical properties of these alloys guarantee sufficient support for the porous structure after depletion of Mg, combining with a low elastic modulus, which renders them potential contenders for use in implants.
- titanium alloy, mechanical property, biomedical implant, corrosion resistance, antimicrobial property