Medical titanium alloys listed in ASTM standards
3 generations for medical titanium alloys
The development of biomedical titanium alloys can be divided into three generations. The first generation is pure titanium and Ti-6A1-4V (mass fraction, the same below). Ti-6A1-4V has good corrosion resistance, low elastic modulus (110-130 GPa) and excellent strength-plasticity matching, and has been widely used in the field of medical metal materials.
However, its elastic modulus is 4-20 times that of human bones, and clinical use has found that AI elements and V elements may cause adverse reactions such as Alzheimer's disease, neurological disorders and osteomalacia.
Subsequently, Germany and Switzerland replaced V with Fe and Nb respectively in the 1980s and developed the second generation of a+β-type medical a represented by Ti-5AI-2.5Fe and Ti-6AI-7Nb. Ti-5A1-2.5Fe and Ti-6AI-7Nb titanium alloys have similar mechanical properties and better physical compatibility as Ti-6AI-4V, but still contain potentially toxic elements A1, and the elastic modulus is still much higher than that of human bones.
In order to further improve the biocompatibility and mechanical compatibility of medical titanium alloys, since the 1990s, countries around the world have successively carried out research on the third B-type medical titanium alloy that does not contain toxic elements such as Al and V and has a lower elastic modulus, and developed a series of new medical titanium alloys, such as Ti-13Nb-13Zr, Ti-12Mo-6Zr-2Fe (TMZF) and Ti-35Nb-7Zr-5Ta (T-Osteum) in the United States and Ti-29Nb-13Ta- 4.6Zr (TNTZ) and Ti-23Nb-0.7Ta-2Zr-1.20 (atomic fraction/%, Gum metal), China's Ti-24Nb-4Zr-7.9Sn (Ti-2448), TLE (Ti-(3~6)Zr-(2~4)Mo-(24~27)Nb) and TLM (Ti-(1.5~4.5)Zr-(0.5 ~5.5)Sn(1 .5 ~4.4)Mo-(23.5~26.5)Nb, etc.
It can be seen that the new generation of medical titanium alloys are mostly Ti-Nb systems, with added bio-friendly elements such as Mo, Ta, Zr and Sn, which have lower elastic modulus and better biocompatibility than pure titanium and medical titanium alloys such as Ti-6A1-4V. Ti-Nb-based titanium alloys can obtain excellent biocompatibility, low elastic modulus, high strength, superelasticity and shape memory effect through alloy composition design and microstructure regulation, and have attracted extensive attention from researchers in the fields of materials and medicine.
