Effect of Nb Content on Microstructures and Mechanical Properties of Ti-xNb-2Fe Alloys
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β-Type Ti-Nb-based alloys exhibit satisfactory biocompatibility and low Young’s modulus for biomedical applications. The microstructure and mechanical properties of a series of Ti-(14, 16, 18, 20, 22, 24)Nb-2Fe alloys fabricated by arc melting were investigated by XRD, optical microscopy, and tensile tests. Both ω and α″ phases existed in the Ti-14Nb-2Fe alloy, while just a single β phase existed in the other alloys. Twinning is an important deformation mechanism that causes work hardening and twinning-induced plasticity. It was found in the Ti-(14, 16, 18, 20)Nb-2Fe alloys and not in the Ti-22Nb-2Fe alloy. The Ti-14Nb-2Fe alloy exhibited the highest tensile strength and the highest Young’s modulus owing to the existence of the ω phase. The tensile strength decreased gradually from 830 MPa (highest) for the Ti-14Nb-2Fe alloy to 540 MPa (lowest) for the Ti-24Nb-2Fe alloy with an increase in the Nb content. The Young’s modulus decreased from 90 GPa for the Ti-14Nb-2Fe alloy to 63 GPa for the Ti-22Nb-2Fe alloy and then increased to 71 GPa for the Ti-24Nb-2Fe alloy. Elongation shows the same trend as the Young’s modulus. The Ti-22Nb-2Fe alloy, with a low Young’s modulus of 63 GPa, tensile strength of 570 MPa, and 15% elongation, was found suitable for biomedical applications. The Ti-20Nb-2Fe alloy also exhibits a high tensile strength, a Young’s modulus ratio of 9.24 × 10−3, and 18% elongation and is thus considered another valuable Ti alloy for biomedical applications.
Keywordsβ stability biomaterials mechanical properties microstructures Ti-Nb alloys
This work was partially supported by the Natural Science Foundation of Shanghai, China (No. 15ZR1428400), Shanghai Key Technology Support Program (No. 16060502400), National Natural Science Foundation of China (No. 61504080, 51771120 and 51304136), the project of Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development, Tohoku University, Japan sponsored by Ministry, Education, Culture, Sports, Science and Technology, Japan, and the Grant-in Aid for Scientific Research (B) (No. 17H03419) from Japan Society for the Promotion of Science (JSPS), Tokyo, Japan.
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