Corrosion resistance of Ti-Fe binary alloys fabricated by powder metallurgy

Wei Xu, Xin Lu, Yanxia Du, Qingyu Meng, Ming Li, Xuanhui Qu

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Titanium and its alloys have been widely used in the biomedical field, and have a great potential in making orthopedic implants due to their high specific strength, low elastic modulus, excellent biocompatibility and corrosion resistance in the human body environment. However, important titanium alloys currently used including extra low interstitial (ELI) Ti-6Al-4V (hereafter all in mass fraction, %), Ti-5Al-2.5Fe and Ti-6Al-7Nb are all at risk of releasing toxic Al and V ions in vivo. In addition, the elastic modulus (about 110 GPa) of these alloys are still much higher than those of cortical bones (about 20 GPa), which may bring severe 'stress shielding' for implantation failures. In order to solve these problems, much effort has been made to develop Al- and V-free lower-modulus β-Ti alloys. Considering that Fe is one of most effective and low-cost β-phase stabilizing element in titanium, binary Ti-Fe alloys have been selected and an assessment of the potential for biomedical applications has been conducted from the perspectives of their manufacturability, mechanical properties and biocorrosion performance. In this study, Ti-xFe (2%≤x≤20%) alloys were fabricated by powder metallurgy, and their microstructure and compression properties were characterized. In particular, the corrosion properties in four different simulated physiological electrolytes at (37±0.5)℃ were investigated according to ASTM 59-97, compared with the performances of two commonly used titanium-based materials Ti-6Al-4V and commercially pure (CP) titanium. The results show that the content of β phase gradually increases with Fe content increasing. When Fe content goes up to 20%, the alloy samples are only composed of single β-phase grains. The PM-fabricated Ti-(2~20)Fe alloy is provided with a superior combination of mechanical properties, with the compressive strength range of 2096.2~2702.3 MPa, the compression ratio of 20.6%~33.2% and the elasticity modulus of 62.7~85.5 GPa. Higher Fe content tends to lead to the higher strength and ductility, but lower elastic modulus. In comparison, Ti-15Fe sintered at 1150℃ exhibits the superior mechanical properties, including the elastic modulus of 64.6 GPa, the compressive strength of 2702 MPa, and the compression rate of 32.7%. With the rise of Fe content in 2%~15%, the corrosion potential of alloys moves to a positive position, and the corrosion current density decreases, corresponding to the increase in the polarization resistance, which suggests the improvement of their corrosion properties. The binary alloy with 20%Fe possesses the similar corrosion performance to that of Ti-15Fe. The corrosion rates of Ti-15Fe alloy in simulated oral solution (FAS), phosphate buffer solution (PBS), simulated body fluid solution (SBF) and 0.9%NaCl solution (SS) are 1.7×10-3, 7.1×10-4, 1.2×10-3 and 3.5×10-4 mm/y, respectively. Compared with CP Ti and Ti-6Al-4V, Ti-15Fe alloy exhibits a more positive corrosion potential, smaller corrosion current density and higher polarization resistance, indicating a superior corrosion resistance.

Original languageEnglish
Pages (from-to)38-46
Number of pages9
JournalJinshu Xuebao/Acta Metallurgica Sinica
Volume53
Issue number1
DOIs
Publication statusPublished - 2017 Jan 11
Externally publishedYes

Keywords

  • Biomedical
  • Corrosion rate
  • Corrosion resistance
  • Powder metallurgy
  • Ti-Fe binary alloy

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

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