Design of bioresorbable magnesium alloy

Abstract

In recent times, Magnesium alloys have been attractive in medical science since they have compatible mechanical properties with the cortical bone and bioresorbable properties. Depending on the fabrication method, alloy element, and coating surface, the degradation rate in the physiological condition can be tailored. The present study investigated the Spark Plasma Sintering (SPS) effect on the entirely newly designed Mg alloy. All alloying elements (Zn, Er and Ce) were chosen based on the Mg matrix’s solubility and their mechanical properties and cytotoxic behaviour in the in-vivo condition. The sintering temperature on the microstructure, hardness and corrosion behaviour of a high-energy ball-milled Mg.67Zn.02Er.2Ce.01 was investigated. Along with that, the effect of alloying elements on the microstructure and radiographic properties was also examined. During the SPS, holding time and sintering pressure kept constant while varying the sintering temperature from 400ᵒC to 420ᵒC. The grain size and microstructure were investigated using optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Corrosion behaviour was studied in the simulated body fluid using the milligram per decimeter per day (MDD) method, and the radiographic property was tested in the soft X-ray range. Vickers hardness and corrosion performance improved for the samples prepared at 420ᵒ C, whereas radiopacity under x-ray increased. A possible reason for strengthening and corrosion behaviour has been discussed in light of reduced porosity and grain size. Alloying bioserobale Mg with rare earth metal-Er can provide duel effects such as bioabsorbility and high radiopacity. So, a positive correlation between the opacity enhancement under the x-ray and the presence of Erbium is also under consideration. Suggestions for future design and processing of Mg alloys for bioresorbable implants are provided. Keywords: Magnesium alloys; Spark Plasma Sintering (SPS); Bioresorbable; Microstructure; Hardness; Corrosion; Radiopacity