Mechanical properties, structural and texture evolution of biocompatible Ti-45Nb alloy processed by severe plastic deformation

Ajit Panigrahi, Bartosz Sulkowski, Thomas Waitz, Kadir Ozaltin, Witold Chrominski, Aurimas Pukenas, Jelena Horky, Malgorzata Lewandowska, Werner Skrotzki, Michael Zehetbauer

Biocompatible beta Ti-45Nb (wt%) alloys were subjected to different methods of severe plastic deformation (SPD) in order to increase the mechanical strength without increasing the low Young's modulus thus avoiding the stress shielding effect. The mechanical properties, microstructural changes and texture evolution were investigated, by means of tensile, microhardness and nanoindentation tests, as well as TEM and XRD. Significant increases of hardness and ultimate tensile strength up to a factor 1.6 and 2, respectively, could be achieved depending on the SPD method applied (hydrostatic extrusion - HE, high pressure torsion - HPT, and rolling and folding - R&F), while maintaining the considerable ductility. Due to the high content of beta-stabilizing Nb, the initial lattice structure turned out to be stable upon all of the SPD methods applied. This explains why with all SPD methods the apparent Young's modulus measured by nanoindentation did not exceed that of the non-processed material. For its variations below that level, they could be quantitatively related to changes in the SPD-induced texture, by means of calculations of the Young's modulus on basis of the texture data which were carefully measured for all different SPD techniques and strains. This is especially true for the significant decrease of Young's modulus for increasing R&F processing which is thus identified as a texture effect. Considering the mechanical biocompatibility (percentage of hardness over Young's modulus), a value of 3-4% is achieved with all the SPD routes applied which recommends them for enhancing beta Ti-alloys for biomedical applications.

Physics of Nanostructured Materials
External organisation(s)
AGH University of Science and Technology, Warsaw University of Technology, Technische Universität Dresden, AIT Austrian Institute of Technology
Journal of the Mechanical Behavior of Biomedical Materials
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
Materials physics
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