Use of first principles and Thermo-Calc to identify potential low elastic modulus titanium-based alloys for biomedical applications

  • M N Madigoe Council for Scientific and Industrial Research
  • R Modiba Council for Scientific and Industrial Research
  • L A Cornish University of the Witwatersrand
Keywords: Titanium alloys, Elastic modulus, First principles, Thermo-Calc

Abstract

High alloyed β-phase stabilised titanium alloys are known to have low elastic moduli comparable to that of the human bone (≈30 GPa). The β-phase in titanium alloys exhibits an elastic modulus of about 60-80 GPa, which is nearly half that of α-phase (100-120 GPa). In this work, an attempt to develop a β-phase titanium-based alloy through first-principles calculations and Thermo-Calc calculations for biomedical applications was conducted. First-principles calculations were performed using the CASTEP code on a simple 2-atom bcc unit cell to predict the theoretical elastic modulus and mechanical stability of the Ti-Nb-Ta-Zr (TNTZ) system at 0 K. Thermo-Calc was used to determine the phase proportion diagrams of the proposed alloys at 500℃. The alloy comprised Ti-Nbx-Ta25-Zr5 (x = 5, 10, 20, 30, 40) (at.%). The theoretical results suggested that increasing niobium content introduced both mechanical (cʹ > 0) stability of the alloys. Alloy Ti-Nb5-Ta25-Zr5 gave the lowest elastic modulus of 55.23 ± 24.45 GPa which is half the elastic modulus of pure titanium (α phase). The phase proportion diagrams showed that up to 58.6 mol.% of β phase was retained at 20 at.% Nb, although the Voigt-Reuss-Hill Young’s modulus calculated from first principles increased with increasing niobium content while the α/β phase transformation temperature decreased down to 551.3℃ at 40 at.% Nb.

Author Biographies

M N Madigoe, Council for Scientific and Industrial Research

Advanced Materials and Engineering, Manufacturing Cluster, Council for Scientific and Industrial Research, Meiring Naudé Road, Brummeria, Pretoria 0185, and School of Chemical and Metallurgical Engineering and DSI NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Johannesburg, South Africa

R Modiba, Council for Scientific and Industrial Research

Advanced Materials and Engineering, Manufacturing Cluster, Council for Scientific and Industrial Research, Meiring Naudé Road, Brummeria, Pretoria 0185, South Africa

L A Cornish, University of the Witwatersrand

School of Chemical and Metallurgical Engineering and DSI-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Johannesburg, South Africa

Published
2022-01-25
How to Cite
Madigoe, M., Modiba, R., & Cornish, L. (2022). Use of first principles and Thermo-Calc to identify potential low elastic modulus titanium-based alloys for biomedical applications. Suid-Afrikaans Tydskrif Vir Natuurwetenskap En Tegnologie / <i>South African Journal of Science and Technology</I&gt;, 40(1), 228-233. Retrieved from http://www.satnt.ac.za/index.php/satnt/article/view/908
Section
Conference of the South African Advanced Materials Initiative

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