Microstructure and mechanical properties of an Mg-3Zn- o.5Zr-5HA nanocomposite processed by ECAE

J Li,Y Huang

doi:10.1088/1757-899x/63/1/012112

Abstract

Mg matrix composites reinforced by natural bone constituent hydroxyapatite (HA) particles have shown promising in-vitro corrosion resistance but are inconsistent in both electrochemical and mechanical performances because of severe particle segregations. The present work was carried out to investigate the feasibility of a novel technology that combines high shear solidification and equal channel angular extrusion (ECAE) for fabricating Mg-HA nanocomposites. Experiments showed that the high shear solidification resulted in a fine and uniform grain structure with a globally uniform HA nanoparticles in fine clusters and the ECAE processing of the as-cast composites resulted in further grain refinement and more importantly the breakdown of nanoparticle aggregates, leading to the formation of a dispersion of true nanoparticles in the Mg alloy matrix with improved mechanical properties. This paper describes mainly the microstructural features and mechanical performance of Mg-3Zn-0.5Zr-xHA (x = 1, 3, 5, 10) nanocomposites, in which the HA was in spherical shape with an average diameter of ~20nm

Highlights

Mg alloys have similar mechanical strength and elastic modulus to those of human bones and are dissolvable in the human fluid environment, representing potentially an advantageous class of biomedical implants over currently used metals, alloys and polymers [1, 2]
Most HA particles for the sheared composites were found in clusters, forming a coarse network that coupled with the grain boundary network for the matrix Mg alloy (Fig. 2c-2f), the maximum cluster size was largely reduced from over 400μm for the non-sheared to about 20μm with much improved local spatial distribution
The present experimental results demonstrated that the combined high shear solidification and equal channel angular extrusion (ECAE) was an effective technology for fabricating Mg-HA nanocomposites with a fine microstructure, uniformly distributed HA particles and enhanced hardness: 1. Mg-3Zn-0.5Zr Mg alloy matrix, HA nanoparticle reinforced composites were successfully fabricated with a range of HA particle weight percentage of up to 10

Summary

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Microstructure and mechanical properties of an Mg-3Zn- o.5Zr-5HA nanocomposite processed by ECAE. This content has been downloaded from IOPscience. Please scroll down to see the full text. 63 012112 (http://iopscience.iop.org/1757-899X/63/1/012112) View the table of contents for this issue, or go to the journal homepage for more. Download details: IP Address: 134.83.1.243 This content was downloaded on 11/08/2014 at 15:19 Please note that terms and conditions apply

Introduction

Findings

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Conclusions