Microstructure, mechanical properties and bio-corrosion evaluation of biodegradable AZ91-FA nanocomposites for biomedical applications

Abstract

Recently, magnesium-based materials have shown the potential to serve as biodegradable metal implant suitable for repair of load-bearing defects in osseous tissue. However, the mechanical properties of magnesium alloys were low for the load-bearing applications, and the corrosion resistance also needed to be improved furthermore. Design and preparing of a nanocomposite based on magnesium alloy might be an approach to this challenge. The aim of this work was to evaluate the effect of fluorapatite (FA) nano-particles content on microstructure, mechanical properties and bio-corrosion behavior of a nanocomposite (AZ91-FA) made of AZ91 magnesium alloy as matrix and FA nano-particles as reinforcement for load-bearing applications. Novel AZ91-FA (with 10 wt.%, 20 wt.%, and 30 wt.% of FA) nanocomposites were produced by AZ91 magnesium alloy powders and FA nano-particles using a blend-press-sinter powder metallurgy (PM) method. Microstructure, mechanical properties and bio-corrosion behavior of the prepared AZ91-FA nanocomposites, and also the AZ91 magnesium alloy as control sample, were evaluated. The results showed that the presence of the FA nano-particles in the AZ91 magnesium alloy matrix led to significant improvement in hardness and elastic modulus. The AZ91-FA nanocomposite with 20 wt.% of the FA nano-particles showed the highest yield strength, and with the increase of the FA content in the AZ91-FA nanocomposites, the ductility decreased. The AZ91-FA nanocomposites presented increased corrosion resistance compared to the AZ91 magnesium alloy and the corrosion resistance of the AZ91-FA nanocomposites increased with an increase in FA content. The AZ91-FA nanocomposite with 20 wt.% of the FA nano-particles showed optimum mechanical properties as well as the corrosion resistance.