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J Mech Behav Biomed Mater. 2017 May;69:203-212. doi: 10.1016/j.jmbbm.2017.01.005. Epub 2017 Jan 5.

Microstructural, mechanical and corrosion characteristics of heat-treated Mg-1.2Zn-0.5Ca (wt%) alloy for use as resorbable bone fixation material.

Author information

1
Department of Mechanical Industrial and Manufacturing Engineering, University of Toledo, Toledo, OH 43606, USA. Electronic address: Hamdy.m.elsayed@gmail.com.
2
Department of Material Science Engineering, The Ohio State University, Columbus, OH 43210, USA. Electronic address: klarner.1@buckeyemail.osu.edu.
3
Yazaki Technical Center America Inc., 3401 Calle Tecate, Camarillo, CA 93012, USA. Electronic address: behrang.poorganji@gmail.com.
4
Department of Plastic Surgery, The Ohio State University, Columbus, OH 43212, USA. Electronic address: David.Dean@osumc.edu.
5
Department of Material Science Engineering, The Ohio State University, Columbus, OH 43210, USA. Electronic address: luo.445@osu.edu.
6
Department of Mechanical Industrial and Manufacturing Engineering, University of Toledo, Toledo, OH 43606, USA. Electronic address: mohammad.elahinia@utoledo.edu.

Abstract

Mg-Zn-Ca alloys have grabbed most of the recent attention in research attempting to develop an Mg alloy for bone fixation devices due to their superior biocompatibility. However, early resorption and insufficient strength remain the main problems that hinder their use. Heat treatment has previously been thoroughly studied as a post-shaping process, especially after the fabrication of complex parts (e.g. porous structures) by 3D-printing or powder metallurgy. In this work, the effect of heat treatment on Mg-1.2Zn-0.5Ca (wt%) alloy's microstructural, mechanical and corrosion properties was studied. The surface morphology of samples was characterized by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Hardness, compression and tensile tests were conducted, while the in vitro corrosion characteristics of the prepared samples were determined using potentiodynamic polarization (PDP) and immersion tests. It was found that increasing the age hardening duration up to 2-5h increased the heat-treated Mg-1.2Zn-0.5Ca alloy's mechanical properties. Further increase in the age hardening duration did not result in further enhancement in mechanical properties. Similarly, heat treatment significantly altered the Mg-1.2Zn-0.5Ca alloy's in vitro corrosion properties. The corrosion rate of the Mg-1.2Zn-0.5Ca alloy after the heat treatment process was reduced to half of that for the as-cast alloy. XRD results showed the formation of biocompatible agglomerations of hydroxyapatite (HA) and magnesium hydroxide (Mg(OH)2) on the corroded surface of the heat-treated Mg-1.2Zn-0.5Ca alloy samples. The performed heat treatment process had a significant effect on both mechanical and corrosion properties of the prepared Mg-1.2Zn-0.5Ca alloy. The age hardening duration which caused the greatest increase in mechanical and the most slowed corrosion rate for Mg-1.2Zn-0.5Ca alloy material was between 2 and 5h.

KEYWORDS:

Bone fixation hardware; Heat treatment; Immersion test; Magnesium alloy; Mechanical strength; Precipitation hardening

PMID:
28088072
DOI:
10.1016/j.jmbbm.2017.01.005
[Indexed for MEDLINE]

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