SEARCH RESULT

Ti–29Nb–13Ta–4.6Zr (TNTZ) composed of non-toxic and non-allergenic Nb, Ta, and Zr alloying elements, has been extensively investigated [1] as an alternative to the conventional metal based biomaterials. TNTZ must combine both excellent mechanical biocompatibility, corrosion resistance, good cell-implant interactions and healing. Microstructural features such as the grain diameter, secondary phases, residual stress, nature of the surface oxide film, and lattice defects can play a major role in determining the physical response of the material that influence the biocompatibility of TNTZ [1,2]. Severe plastic deformation (SPD) has been a proven technique for controlling the grain size in ultrafine-grained (UFG) (<1000 nm) and/or nanograined (NG) (<100 nm) scale [3]. Furthermore, the influence of ultrafine graining and nanograining on corrosion resistance differs among metallic materials [4,5]. Thorpe et al. [4] reported that there is no differences in corrosion resistance in Ni-based metallic materials and pure Cu. On the other hand, Rofagha et al.[5] reported lower corrosion resistance in nanocrystalline Ni-P compared to the conventional polycrystalline Ni. Clearly, there is a strong connection between corrosion resistance and the microstructural features of metallic materials. Moreover, UFG/NS materials exhibits higher cell attachments compared to their course grained (CG) counterparts [6]. It is well known that high pressure torsion (HPT) is an effective processing for producing NG TNTZ [7]. In this study, the microstructural evolution and its effect on electrochemical behaviour of solution treated TNTZ (TNTZST) and aging treated TNTZ (TNTZAT) subjected to HPT processing were evaluated by electrochemical impedance spectroscopy (EIS) measurements in simulated body fluid (SBF). While TNTZST exhibited a single β body centred cubic (BCC) grain structure having a diameter of 40 µm, the microstructure of TNTZAT consisted of randomly distributed needle-like α (HCP) precipitates in the equiaxed β grains having a diameter of 40 µm. The microstructure of TNTZAHPT consists of NG elongated β grains with a 50 nm having subgrains of non-uniform morphologies resulting from distortion by severe torsional deformation.

International Symposium on Light Alloys and Composite Materials
UHAKS

Hakan Yilmazer Burak Dikici Mitsuo Niinomi Masaaki Nakai

In early 2016, the BBC Horizons aired a reportage about a special metal bone screw implanted in the broken finger bone of a male Korean patient 1 The patient returned to the hospital four months after the surgery with a smiling face because his broken bone had been healed and he did not need to go for a second surgery as the screw has gone away. This media highlight is an example demonstrating that the biomedical device industries are constantly making innovation to provide patients and clinicians with advanced products. In this case, a new generation of metal implants that dissolve in the body after providing the needed function, eliminating the harmful potential effects of permanent metal implants. After decades of acknowledging that metal implants must be corrosion resistant, nowadays corrodible metals are considered for medical applications. The interest toward these corrodible or absorbable metals has been marked by the rapid increase of related scientific publications and the recent development of new standards on its materials, process, and testing procedures by the ASTM subcommittee F04.15 2-3. Today, at least two medical companies have launched their commercial absorbable metal products.

International Symposium on Light Alloys and Composite Materials
UHAKS

Hendra Hermawan Hakan Yilmazer

β-type titanium alloys have been developed all over the world, which widely used in several biomedical applications because of their good mechanical properties such as low Young’s modulus and corrosion resistance [1]. Niinomi et al. has also developed a β-type Ti-29Nb-13Ta-4.6Zr, referred to as TNTZ, which is composed of non-toxic and non-allergic elements such as Nb, Ta, and Zr, with low Young’s modulus [2]. It was also revealed that the cell viability on TNTZ is much superior than that on Ti-6Al-4V ELI [2,3]. Young’s modulus of TNTZ subjected has been found to be around 60 GPa at the microstructure having single β (BCC) phase for solution treatment and cold rolling [4-5]. It is much more closer to those (10-30 GPa) of bone than those (100 and 110 GPa) of commercial pure Ti and Ti-6Al-4V ELI.

International Symposium on Light Alloys and Composite Materials
UHAKS

Hakan Yilmazer Mazin Abed Mitsuo Niinomi Masaaki Nakai Huseyin Cimenoglu Murat Baydogan