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. 2019 Jul 1;5(2):207.
doi: 10.18063/ijb.v5i2.207. eCollection 2019.

A continuous net-like eutectic structure enhances the corrosion resistance of Mg alloys

Cijun Shuai  1   2   3 , Wenjing Yang  1   2 , Youwen Yang  2 , Chengde Gao  1 , Chongxian He  2 , Hao Pan  4
Affiliations

A continuous net-like eutectic structure enhances the corrosion resistance of Mg alloys

Cijun Shuai et al. Int J Bioprint. .

Erratum in

  • ERRATUM.
    [No authors listed] [No authors listed] Int J Bioprint. 2020 Sep 17;6(4):309. doi: 10.18063/ijb.v6i4.309. eCollection 2020. Int J Bioprint. 2020. PMID: 33102924 Free PMC article.

Abstract

Mg alloys degrade rather rapidly in a physiological environment, although they have good biocompatibility and favorable mechanical properties. In this study, Ti was introduced into AZ61 alloy fabricated by selective laser melting, aiming to improve the corrosion resistance. Results indicated that Ti promoted the formation of Al-enriched eutectic α phase and reduced the formation of β-Mg17Al12 phase. With Ti content reaching to 0.5 wt.%, the Al-enriched eutectic α phase constructed a continuous net-like structure along the grain boundaries, which could act as a barrier to prevent the Mg matrix from corrosion progression. On the other hand, the Al-enriched eutectic α phase was less cathodic than β-Mg17Al12 phase in AZ61, thus alleviating the corrosion progress due to the decreased potential difference. As a consequence, the degradation rate dramatically decreased from 0.74 to 0.24 mg·cm-2·d-1. Meanwhile, the compressive strength and microhardness were increased by 59.4% and 15.6%, respectively. Moreover, the Ti-contained AZ61 alloy exhibited improved cytocompatibility. It was suggested that Ti-contained AZ61 alloy was a promising material for bone implants application.

Keywords: corrosion resistance; eutectic α; mg alloys; net-like structure; phase; selective laser melting.

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Figures

Figure 1
Figure 1
Morphologies of original powders: (A) AZ61, (B) Ti and (C) AZ61-0.5Ti mixed powder; (D)-(F) were the element distributions of Mg, Al, and Ti of AZ61-0.5Ti mixed powder.
Figure 2
Figure 2
(A) Microstructure of AZ61-Ti observed under scanning electron microscope and the corresponding elemental distribution of Al; red arrow indicates the eutectic α phase. (B) Energy dispersive spectroscopy results corresponding to particles in Figure 2A.
Figure 3
Figure 3
Optical microstructure of (A) AZ61, (B) AZ61-0.25Ti, (C) AZ61-0.5Ti, (D)AZ61-0.75Ti, and (E) AZ61-1.0Ti. (F) The measured average grain sizes. (G) X-ray diffraction patterns of AZ61-Ti. Mg17Al12 and TiAl3 phases were marked by black dash arrow and red solid arrow, respectively.
Figure 4
Figure 4
Electrochemical testing results of AZ61-Ti: (A) open circuit potential curves, (B) potentiodynamic polarization curves, (C) Ecorr and (D) icorr derived from the potentiodynamic polarization curves by Tafel extrapolation.
Figure 5
Figure 5
Immersion degradation behaviors of AZ61-Ti: (A) Hydrogen evolution volumes, (B) pH during immersion, (C) ion-releasing behavior during immersion, and (D) corrosion rate calculated from the mass loss.
Figure 6
Figure 6
Corrosion surfaces of (A) AZ61, (B) AZ61-0.25Ti, (C) AZ61-0.5Ti, (D) AZ61-0.75Ti, and (E) AZ61-1.0Ti observed under scanning electron microscope after immersion for 2 and 7 days; (F) energy dispersive spectroscopy results of specific areas in AZ61-0.5Ti.
Figure 7
Figure 7
(A) pH of the extracts; (B) Mg and Zn concentration in the extracts; (C) relative viability of MG63 cells culture in AZ61-Ti extracts.
Figure 8
Figure 8
LIVE/DEAD staining of MG63 cells seeded in AZ61-Ti 100% extracts for 24 h and 72 h.
Figure 9
Figure 9
Mechanical performances of AZ61-Ti: (A) Compression strength and (B) microhardness.
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