Selective laser melting of high-strength, low-modulus Ti–35Nb–7Zr–5Ta alloy

Research output: Contribution to journalArticleResearchpeer-review

Authors

  • Raghunandan Ummethala
  • Phani S. Karamched
  • Sokkalingam Rathinavelu
  • Neera Singh
  • Akash Aggarwal
  • Kang Sun
  • Eugene Ivanov
  • Lauri Kollo
  • Ilya Okulov
  • K. G. Prashanth

Organisational units

External Organisational units

  • Department of Metallurgical and Materials Engineering
  • University of Oxford
  • National Institute of Technology, Tiruchirappalli
  • Department of Materials Science and Engineering, Ghent University
  • Leibniz Institute for Solid State and Materials Research, Dresden
  • Tosoh SMD Inc.
  • Ural Federal University
  • Erich Schmid Institute of Materials Science
  • VIT University
  • Leibniz Institute for Materials Engineering IWT
  • Tallinn University of Technology

Abstract

The state-of-the-art alloys for load-bearing implant applications lack the necessary functional attributes and are largely a compromise between biocompatibility and mechanical properties. While commercial alloys pose long-term toxicity and detrimental stress shielding effects, the newly developed alloys are closing in on the gaps, however, falling short of the desired elastic modulus necessary to rule out stress shielding. In this work, we report the fabrication of a low modulus β-Ti alloy, Ti–35Nb–7Zr–5Ta (TNZT), by selective laser melting (SLM) with optimized laser parameters. The as-prepared SLM TNZT shows a high ultimate tensile strength (~630 MPa), excellent ductility (~15%) and a lower elastic modulus (~81 GPa) when compared to the state-of-the-art cp-Ti and Ti-based alloys. The mechanical performance of the as-printed TNZT alloy has been examined and is correlated to the microstructure (grain structure, phase constitution and dislocation density). It is proposed that a high density of GND (geometrically necessary dislocations), resulting from rapid cooling, in the as-prepared condition strengthens the alloy, whereas the single phase β-bcc crystal structure results in lowering the elastic modulus. High grain boundary area and a preferred crystal orientation of {200} planes within the bcc crystal lattices contribute to an additional drop in the elastic modulus of the alloy. It is shown that the TNZT alloy, processed by SLM, demonstrates the best combination of strength and modulus, illustrating its potential as a promising biomaterial of the future.

Details

Original languageEnglish
Article number100941
JournalMaterialia
Volume14.2020
Issue numberDecember
Early online date23 Oct 2020
DOIs
Publication statusPublished - Dec 2020