Medical implanted titanium alloy with low elastic modulus and high fatigue strength and preparation method

Abstract

The invention relates to a medical implanted titanium alloy with low elastic modulus and high fatigue strength and a preparation method. The medical implanted titanium alloy comprises, by weight, 30-33% of Nb, 1-6% of Zr, 2-4% of Mo, 0.20-0.40% of O, and the balance Ti. The preparation method of the medical implanted titanium alloy specifically comprises the steps that smelting is conducted by using a vacuum non-consumable electric-arc furnace to obtain an alloy ingot with uniform ingredients, solution treatment is conducted at 850-950 DEG C after the alloy ingot is subjected to hot forging into bar materials, and water cooling is conducted to the room temperature; then cold rolling deformation processing is conducted, and the deformation quantity is 80-90%; and finally, aging heat treatment is conducted, the heating temperature of the aging heat treatment is 400-500 DEG C, and the heat preservation time is 1-12 h. According to the medical implanted titanium alloy with the low elasticmodulus and the high fatigue strength and the preparation method, after cold rolling and heat treatment, the strength is significantly higher than that of a current most-widely-applied medical implanted titanium alloy Ti-6Al-4V, the fatigue strength is comparable to Ti-6Al-4V, the elastic modulus is only 52% of Ti-6Al-4V, the biocompatibility and the mechanical compatibility are more excellent, and the medical implanted titanium alloy can be applied to preparation of biomedical implants.

Description

technical field [0001] The invention relates to a medical implant titanium alloy with low elastic modulus and high fatigue strength and a preparation method thereof, belonging to the technical field of design and preparation of titanium alloy materials. Background technique [0002] Titanium and its alloys have excellent mechanical properties and high corrosion resistance in body fluid environments, and are the materials of choice for the repair and replacement of human hard tissues such as artificial joints and dental implants. Ti-6Al-4V has high tensile strength (895MPa-930MPa) and excellent fatigue performance (at a stress ratio of 0.1 and a cycle of 10 7 Under certain conditions, the fatigue limit reaches 470-540MPa), which can ensure that no fatigue fracture occurs after serving in the human body for more than 20 years. It is currently the most widely used planting material. However, the existing problems of Ti-6Al-4V are: ① The alloy contains V and Al elements that ar...

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Problems solved by technology

However, the existing problems of Ti-6Al-4V are: ① The alloy contains V and Al elements that are harmful to the human body, especially V has cytotoxicity, and there are potential safety hazards in long-term use

② The alloy is mainly composed of α phase with high elastic modulus. The elastic modulus of the alloy (106GPa) is much higher than that of human bone (10-30GPa). The serious mismatch of elastic modulus causes "stress" at the interface between the implant and the bone. Shielding effect”, long-term use will cause bone resorption and osteoporosis, resulting in aseptic loosening of the implant and shortening the service life

[0004] However, there are still some problems in the current research on the new medical low elastic modulus β titanium alloy: ① When the elastic modulus of the alloy in the solid solution state (composed of β phase) decreases to 55GPa-65GPa, its tensile strength also decreases simultaneously (generally less than 800MPa), can not meet the strength requirements

②Through 80-90% high deformation rate cold rolling deformation of solid solution alloy, the tensile strength can be significantly improved and the elastic modulus can be reduced, but due to the large deformation cold rolling, the crystal defect density is high, the residual stress is large, and the plasticity Poor, the fatigue performance is significantly lower than that of Ti-6Al-4V alloy, and it loses its use value

For example, Japan has cold-rolled the Ti-29Nb-13Ta-4.6Zr alloy with a deformation rate of 87.5%. The tensile strength reaches 830MPa and the elastic modulus is 60GPa, but the fatigue strength is only 360MPa (stress ratio 0.1, cycle times 10 7 ), significantly lower than the fatigue strength of Ti-6Al-4V alloy (Akahori T, Niinomi M, Fukui H, et al, Improvement in fatigue characteristics of newly developed beta type titanium alloy for biomedical applications by thermo-mechanical treatments, Materials Science & Engineering C, 2005 ,25:248-254)

③The tensile strength and fatigue strength can be significantly improved by performing conventional aging heat treatment at 400°C-450°C on solid solution or cold-rolled alloys, but due to the large amount of α-phase with high elastic modulus precipitated, the elastic modulus of the alloy is usually When it rises above 80GPa, it loses the characteristics of low elastic modulus medical implant titanium alloy

As far as the existing literature reporting its fatigue properties is concerned, it is still difficult to resolve the contradiction between the low elastic modulus and high strength and high fatigue properties of the new β titanium alloy

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