Title: Effect of high-pressure torsion processing on microstructure and mechanical properties of a novel biomedical β-type Ti-29Nb-13Ta-4.6Zr after cold rolling

Authors: Hakan Yilmazer; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Yoshikazu Todaka

Addresses: Department of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-ku Katahira 2-1-1, Sendai 980-8577, Japan. ' Institute for Materials Research, Tohoku University, Aoba-ku Katahira 2-1-1, Sendai 980-8577, Japan. ' Department of Materials Science and Engineering, Faculty of Materials Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tempa-ku, Nagoya 468-8502, Japan. ' Institute for Materials Research, Tohoku University, Aoba-ku Katahira 2-1-1, Sendai 980-8577, Japan. ' Department of Production System Engineering, Toyohashi University, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan

Abstract: High mechanical biocompatibility, which implies excellent mechanical properties such as great strength and hardness with keeping low Young's modulus in a new biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), can be achieved by microstructural control. Strengthening of TNTZ by grain refinement and increasing dislocation density is expected to provide high mechanical strength with keeping low Young's modulus because they maintain the original β phase. In this case, high-pressure torsion (HPT) processing is one of the effective ways to obtain these properties simultaneously in this alloy. This study systematically investigated the effect of HPT processing on the microstructure and the mechanical properties of TNTZ. The microstructure of TNTZ, which was subjected to HPT processing after cold rolling, exhibits a single β phase composed of grains with diameter of less than a few hundred nanometres and high-angle boundaries. The grains have non-uniform subgrains with high angle misorientation and high dislocation density due to severe plastic deformation. The tensile strength of the specimen after HPT processing increases significantly compared with the specimen processed by cold rolling.

Keywords: metallic biomaterials; beta-type titanium alloys; severe plastic deformation; SPD; Ti-29Nb-13Ta-4.6Zr; TNTZ; high-pressure torsion; HPT; nanostructure; microstructure; mechanical properties; cold rolling; biocompatibility; tensile strength.

DOI: 10.1504/IJMMP.2012.047498

International Journal of Microstructure and Materials Properties, 2012 Vol.7 No.2/3, pp.168 - 186

Published online: 24 Jun 2012 *

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