Effect of Processing Mg-6zn-0.2ce Through High-pressure Torsion on Its Use as a Biomaterial

Abstract

Here, we investigate the effect of high-pressure torsion (HPT), a severe plastic deformation process, on the mechanical properties, corrosion, and cytotoxicity of Mg-6Zn-0.2Ce alloy, a candidate material for bioresorbable bone implants. This alloy was processed by quasi-constrained HPT by applying a pressure of 6 GPa at room temperature for 1, 2, and 5 turns. Samples processed to two turns of HPT showed the smallest grain size, the highest strength that was approximately five times higher than the as-received coarse-grained sample and a reduction in the ductility. Electrochemical impedance spectroscopy and potentiodynamic polarization demonstrated the highest corrosion resistance for the Mg-alloy processed for two turns of HPT; however, accelerated degradation due to pitting corrosion was observed after immersion in simulated body fluid (SBF) for three days. Nevertheless, all HPT-processed samples showed lower corrosion rates in all corrosion tests compared to their annealed counterparts. Finally, cell culture revealed good cytocompatibility without any noticeable changes in cytotoxicity following HPT processing. Overall, HPT for two turns showed enhanced strength and reduced corrosion rates without loss in cytocompatibility for the Mg-6Zn-0.2Ce alloy, making it a promising strategy to enhance the performance of the alloy as a bioresorbable orthopedic biomaterial. This work highlights the potential of HPT as a viable technique to improve the biomedical performance of Mg alloys for engineering next-generation biomedical implants.