Scientia Iranica

Scientia Iranica

Volume 20, Issue 3, June 2013, Pages 1067-1070
Scientia Iranica

Research note
Heterogeneous grain refinement of biomedical Ti–29Nb–13Ta–4.6Zr alloy through high-pressure torsion

https://doi.org/10.1016/j.scient.2013.01.004Get rights and content
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Abstract

The biomedical β-type titanium alloy Ti–29Nb–13Ta–4.6Zr (TNTZ) exhibits non-toxicity and a low Young’s modulus that is similar to that of bone. This alloy has a low Young’s modulus because it contains a metastable β phase. Strengthening due to grain refinement tends to provide high mechanical strength, while keeping the Young’s modulus low, because it maintains the original β phase. In this case, severe plastic deformation, such as High-Pressure Torsion (HPT), is a potential treatment for obtaining these properties simultaneously. Thus, in this study, the effect of HPT on the microstructure and hardness of TNTZ was systematically investigated. On the cross sections of TNTZ subjected to HPT, heterogeneous microstructures, consisting of a matrix and an unetched band not corroded by an etching solution, were observed. Both the matrix and the unetched band were comprised of a single β phase with submicron-sized grains, but their grain geometries differed: equiaxed grains and elongated grains are observed in the matrix and the unetched band, respectively. The hardness distribution in the cross section of TNTZ subjected to HPT is also heterogeneous; the hardness is higher in the matrix than in the unetched band, when the number of HPT rotations is small.

Keywords

Biomaterial
β-type titanium alloy
Severe plastic deformation
Grain refinement

Cited by (0)

Masaaki Nakai received his Ph.D. degree from Nagoya University in 2005, and is currently Associate Professor at the Institute for Materials Research, Tohoku University, Japan. From 2005 to 2006, he was a research fellow of the Japan Society for the Promotion of Science (JSPS), and, then, a research associate and Assistant Professor in the Institute for Materials Research at Tohoku University, Japan. His research is mainly focused on: development of titanium alloys for biomedical applications.

Mitsuo Niinomi earned his Ph.D. degree from the Department of Metallurgical Engineering, and Steel and Iron Engineering, at Nagoya University, Japan, in 1980. He served as Professor at Toyohashi University of Technology and, subsequently, in 2005, at the Institute for Materials Research, Tohoku University, where he was elected Director in 2009. He served as foreign researcher at Wright Patterson Air Force Base, USA, in 1997, and as Visiting Associate Professor and Professor at Carnegie-Mellon University, USA, from 1988 to 1989, and the University of Dayton, USA, respectively. He has been serving as Visiting Professor at Northeastern University, China, since 2010. His research interests include: areas of fracture and microstructure relations of materials, especially titanium alloys for structural and biomedical applications, specifically focusing on the design, development and evaluation of the biological and mechanical biocompatibility of titanium alloys for medical and dental applications.

Junko Hieda received a Ph.D. degree in Engineering from Nagoya University in Japan, and is now working at the Institute for Materials Research in Tohoku University, Japan, as Assistant Professor. She is a member of the Japan Institute of Metal (JIM) and the Japanese Society for Biomaterials (JSB). She has published papers in the area of surface treatment, especially the surface functionalization of metals and preparation of metal nanoparticles by plasma in liquid phase.

Hakan Yilmazer received B.S. and M.S degrees from the Department of Metallurgical and Materials Engineering at Istanbul Technical University, Turkey, in 2006 and 2008, respectively. He started as a research assistant in the Department of Materials Science at Tohoku University, supported by the program of Global Certificate of Excellence (GCOE) of the Japanese Government. He was admitted as a doctoral student at the Niinomi Laboratory in the Graduate School of Engineering at Tohoku University, Japan, in 2008. His research interests include: biomaterials, titanium based biomaterials, severe plastic deformation, nanostructuring, and nitriding.

Yoshikazu Todaka received his B.S., M.S. and Ph.D. degrees in Engineering from Toyohashi University of Technology in Aichi, Japan. He is a member of TMS (Minerals, Metals and Materials Society), JIM (Japan Institute of Metals), and ISIJ (Iron and Steel Institute of Japan). He has published approximately 100 articles on various aspects of nanoparticles, thermoelectric materials and property/microstructure controls by means of severe plastic deformation (SPD). He is also owner of patents in the fields of thermoelectric materials and property/microstructure controls by means of SPD.

Peer review under responsibility of Sharif University of Technology.

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