Effects of Ga on the structural, mechanical and electronic properties of β-Ti-45Nb alloy by experiments and ab initio calculations

Ludovico Andrea Alberta; Yannick Fortouna; Jithin Vishnu; Stefan Pilz; Annett Gebert; Christina Lekka; Kornelius Nielsch; Mariana Calin

doi:10.1016/j.jmbbm.2023.105728

Effects of Ga on the structural, mechanical and electronic properties of β-Ti-45Nb alloy by experiments and ab initio calculations

J Mech Behav Biomed Mater. 2023 Apr:140:105728. doi: 10.1016/j.jmbbm.2023.105728. Epub 2023 Feb 13.

Authors

Ludovico Andrea Alberta¹, Yannick Fortouna², Jithin Vishnu³, Stefan Pilz³, Annett Gebert³, Christina Lekka⁴, Kornelius Nielsch⁵, Mariana Calin³

Affiliations

¹ Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research (IFW) Dresden e.V., Helmholtzstraße 20, Dresden, 01069, Germany. Electronic address: l.a.alberta@ifw-dresden.de.
² University of Ioannina, Department of Materials Science & Engineering, Ioannina, 45110, Greece.
³ Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research (IFW) Dresden e.V., Helmholtzstraße 20, Dresden, 01069, Germany.
⁴ University of Ioannina, Department of Materials Science & Engineering, Ioannina, 45110, Greece; University Research Center of Ioannina (URCI), Institute of Materials Science and Computing, Ioannina, 45110, Greece.
⁵ Institute for Metallic Materials, Leibniz Institute for Solid State and Materials Research (IFW) Dresden e.V., Helmholtzstraße 20, Dresden, 01069, Germany; Institute of Materials Science, Technische Universität Dresden, Helmholtzstraße 7, Dresden, 01062, Germany; Institute of Applied Physics, Technische Universität Dresden, Nöthnitzer Straße 61, Dresden, 01062, Germany.

PMID: 36827933
DOI: 10.1016/j.jmbbm.2023.105728

Abstract

This work aims to investigate the structural, mechanical and electronic properties of four novel β-type (100-x)(Ti-45Nb)-xGa alloys (x = 2, 4, 6, 8 wt%) for implant applications by means of experimental and theoretical (ab initio) methods. All alloys retain the bcc β phase in the solution-treated and quenched state while the lattice parameter decreases with increase in Ga content. This is due to its smaller atomic radius compared to Ti and Nb, in line with the present density functional theory (DFT) calculations. Tensile and microhardness tests indicate a clear strengthening effect with increasing Ga content, with yield strengths in the range 551 ÷ 681 MPa and microhardness in the range 174 ÷ 232 HV_0.1, mainly attributed to grain refinement and solid solution strengthening. Ga also positively affects ductility, with a maximum value of tensile strain at fracture of 32%. Non-destructive ultrasonic measurements and DFT calculations reveal that the bulk modulus is unaffected by the Ga presence. This phenomenon might be due to the fact that Ga introduced bonding and anti-bonding electron low energy states which balance the average bond strength among the atoms in the metallic matrix. Nevertheless, the introduction of new Ga-Ti super sp-like bonding orbitals along the [110] and [-110] directions in the Ga neighborhood could explain the increase of the Young's modulus upon Ga addition (73 ÷ 82.5 GPa) that was found experimentally in the present work. Hence, Ga addition to Ti-45Nb leads to a suitable balance between increased strength and low Young's modulus.

Keywords: Ab initio; Beta-Ti alloys; Biomaterial; Gallium; Implant applications; Mechanical properties.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Alloys* / chemistry
Elastic Modulus
Prostheses and Implants
Tensile Strength
Titanium* / chemistry

Substances

Alloys
Titanium