Perspectives on Titanium Science and Technology

Ti-based alloys are finding ever-increasing applications in biomaterials due to their excellent mechanical, physical and biological performance. Nowdays, low modulus β-type Ti-based alloys are still being developed. Meanwhile, porous Ti-based alloys are being developed as an alternative orthopedic implant material, as they can provide good biological fixation through bone tissue ingrowth into the porous network. This paper focuses on recent developments of biomedical Ti-based alloys. It can be divided into four main sections. The first section focuses on the fundamental requirements titanium biomaterial should fulfill and its market and application prospects. This section is followed by discussing basic phases, alloying elements and mechanical properties of low modulus β-type Ti-based alloys. Thermal treatment, grain size, texture and properties in Ti-based alloys and their limitations are dicussed in the third section. Finally, the fourth section reviews the influence of microstructural configurations on mechanical properties of porous Ti-based alloys and all known methods for fabricating porous Ti-based alloys. This section also reviews prospects and challenges of porous Ti-based alloys, emphasizing their current status, future opportunities and obstacles for expanded applications. Overall, efforts have been made to reveal the latest scenario of bulk and porous Ti-based materials for biomedical applications.

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New Developments of Ti-Based Alloys for Biomedical Applications

The design of new low-cost Ti-alloys with high biocompatibility for implant applications, using ubiquitous alloying elements in order to establish the strategic method for suppressing utilization of rare metals, is a challenge To meet the demands of longer human life and implantation in younger patients, the development of novel metallic alloys for biomedical applications is aiming at providing structural materials with excellent chemical, mechanical and biological biocompatibility It is, therefore, likely that the next generation of structural materials for replacing hard human tissue would be of those Ti-alloys that do not contain any of the cytotoxic elements, elements suspected of causing neurological disorders or elements that have allergic effect Among the other mechanical properties, the low Young's modulus alloys have been given a special attention recently, in order to avoid the occurrence of stress shielding after implantation Therefore, many Ti-alloys were developed consisting of biocompatible elements such as Ti, Zr, Nb, Mo, and Ta, and showed excellent mechanical properties including low Young's modulus However, a recent attention was directed towards the development of low cost-alloys that have a minimum amount of the high melting point and high cost rare-earth elements such as Ta, Nb, Mo, and W This comes with substituting these metals with the common low cost, low melting point and biocompatible metals such as Fe, Mn, Sn, and Si, while keeping excellent mechanical properties without deterioration Therefore, the investigation of mechanical and biological biocompatibility of those low-cost Ti-alloys is highly recommended now lead towards commercial alloys with excellent biocompatibility for long-term implantation

Biocompatibility of Ti-alloys for long-term implantation.

A Review on Biomedical Titanium Alloys: Recent Progress and Prospect

A new look at biomedical Ti-based shape memory alloys

General approach to phase stability and elastic properties of β-type Ti-alloys using electronic parameters

Phase stability change with Zr content in β-type Ti–Nb alloys

High Zr-containing β-type Ti-based alloys were designed using electronic parameters to investigate experimentally the effect of β-phase stability on their elastic and plastic properties. Texture structures formed by cold rolling or recrystallization were related closely to the β-phase stability and hence affected the mechanical properties. In tensile tests, as the β-phase stability decreased, non-linearity in the elastic zone was enhanced and the work hardening tended to be diminished. Also, it was found that the lower β-phase stability led to the weaker anisotropy of plastic properties, but to the stronger anisotropy of elastic properties.

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Keita Hinoshita

Papers

General approach to phase stability and elastic properties of β-type Ti-alloys using electronic parameters

Phase stability change with Zr content in β-type Ti–Nb alloys

Change in anisotropy of mechanical properties with β-phase stability in high Zr-containing Ti-based alloys