Invited Speaker

Abstract: Biodegradable metallic materials such as magnesium (Mg)-based alloys have attracted extensive interest for use as bone implant materials. However, the high biodegradation rate of existing Mg alloys in the physiological environment of human body leads to losing mechanical integrity before adequate bone healing and producing a large volume of hydrogen gas. Therefore, slowing down the biodegradation rate of Mg alloys is a critical task in developing new biodegradable Mg alloy implant materials. One of the most effective approaches to achieve this is to strategically design new Mg alloys with low biodegradation rate, excellent biocompatibility, and enhanced mechanical properties. Our research selected biocompatible and biofunctional alloying elements such as zirconium (Zr), strontium (Sr), and rare earth elements (REEs) to alloy Mg and has developed a new series of Mg-Zr-Sr-REEs alloys for biodegradable implant applications. Research results indicated that Sr and Zr additions can refine the grain size, decrease the biodegradation rate, and enhance the biological behaviors of the Mg alloys. This study systematically investigates the microstructure, mechanical properties, corrosion behavior, and biocompatibility of Mg-based alloys with the addition of different concentrations of scandium (Sc), i.e., Mg-0.6Zr-0.5Sr-xSc (x=0.5, 1, 2, 3 wt.%). Results indicated that high concentration of Sc in strontium (Sr)-containing Mg alloys can alter their microstructures by suppressing the intermetallic phases along the grain boundaries and improve the corrosion resistance by forming chemically stable Sc oxide layers on the surfaces of the Mg alloys. Cytotoxicity assessment revealed that the Sc containing Mg alloys did not significantly alter the viability of human osteoblast-like SaOS2 cells. This study highlights the advantages of using Sc as an alloying element to simultaneously tune Mg alloys with higher strength and slower degradation.

Keywords: Biocompatibility, magnesium, mechanical and biodegrade properties, rare earth elements.

Acknowledgements: The authors acknowledge the financial support for this research by the Australian Research Council (ARC) through the Future Fellowship (FT160100252) and the Discovery Project (DP170102557).

Biography: Dr Yuncang Li is an ARC Future Fellow and Associate Professor at School of Engineering, RMIT University, Australia. He obtained his PhD in Materials Science Engineering from Deakin University in 2004 and then took up a research position in Biomaterials Engineering at Deakin University until the end of 2014. He joined RMIT University in 2015. He was awarded an Australian Research Council (ARC) Future Fellowship in 2016. Dr Li has won a number of national competitive grants including ARC and National Health and Medical Research Council (NHMRC) projects. His research focuses on developing metallic biomaterials for medical applications. He published over 200 journal papers and 15 book chapters and filed 5 patents. He has expertise in microstructure-mechanical property relationships, corrosion, and biocompatibility, surface modification, nanostructured metals and alloys, and metal foams.