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. 2019 Aug 16;12(16):2609.
doi: 10.3390/ma12162609.

Magnesium-Based Bioactive Composites Processed at Room Temperature

Moara M Castro  1 , Debora R Lopes  2 , Renata B Soares  2 , Diogo M M Dos Santos  1 , Eduardo H M Nunes  1 , Vanessa F C Lins  2 , Pedro Henrique R Pereira  1 , Augusta Isaac  1 , Terence G Langdon  3 , Roberto B Figueiredo  4
Affiliations

Magnesium-Based Bioactive Composites Processed at Room Temperature

Moara M Castro et al. Materials (Basel). .

Abstract

Hydroxyapatite and bioactive glass particles were added to pure magnesium and an AZ91 magnesium alloy and then consolidated into disc-shaped samples at room temperature using high-pressure torsion (HPT). The bioactive particles appeared well-dispersed in the metal matrix after multiple turns of HPT. Full consolidation was attained using pure magnesium, but the center of the AZ91 disc failed to fully consolidate even after 50 turns. The magnesium-hydroxyapatite composite displayed an ultimate tensile strength above 150 MPa, high cell viability, and a decreasing rate of corrosion during immersion in Hank's solution. The composites produced with bioactive glass particles exhibited the formation of calcium phosphate after 2 h of immersion in Hank's solution and there was rapid corrosion in these materials.

Keywords: bioactive glass; biodegradable material; composites; high-pressure torsion; hydroxyapatite; magnesium.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Particles used as starting materials.
Figure 2
Figure 2
SEM backscattered electron image of the mid-radius area of the Mg-HA composite.
Figure 3
Figure 3
EDS composition maps taken at a selected area of the Mg-HA composite.
Figure 4
Figure 4
SEM backscattered electron images of areas near the centre (left) and at the mid-radius position (right) of the Mg-BG composite.
Figure 5
Figure 5
SEM images using backscattered electrons (left) and secondary electrons (right) of the AZ91-BG composite.
Figure 6
Figure 6
Microhardness distribution along the disc diameter in the different Mg composites.
Figure 7
Figure 7
Electrochemical impedance spectroscopy tests in Hank’s solution for the different composites. The value for bulk Mg processed by HPT [32] is also shown for comparison.
Figure 8
Figure 8
Low (left) and high (right) magnification images of the surface of the Mg-BG composite after 2 h of immersion in Hank’s solution.
Figure 9
Figure 9
EDS mapping of an area of localized corrosion in the Mg-BG composite after 2 h of immersion in Hank’s solution.
Figure 10
Figure 10
Low (left) and high (right) magnification images of the surface of the AZ91-BG composite after 2 h of immersion in Hank’s solution.
Figure 11
Figure 11
Low (left) and high (right) magnification images of the surface of the Mg-HA composite after 6 h of immersion in Hank’s solution.
Figure 12
Figure 12
Hydrogen evolution as a function of time for the Mg-HA composite immersed in Hank’s solution.
Figure 13
Figure 13
Stress vs. strain curve for the Mg-HA composite.
See this image and copyright information in PMC

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