Mechanical Properties, Corrosion and Microstructure of Mg/2FA/0.3GNPs (wt.%) Hybrid Nanobiocomposite Produced by Mechanical ‎Stir Casting and Remelting under Argon Pressure‎

Hybrid nano-biocomposite of Mg-0.5Ca-0.8Mn (wt%) magnesium alloy reinforced by 2 wt% fluorapatite (FA) nanoparticles and 0.3 wt% graphene nanoplates (GNPs) were prepared via mechanical stir casting process. In order to eliminate the casting defects, remelting process was carried out under argon atmosphere. Mechanical and biocorrosion properties were investigated by tensile testing and electrochemical impedance spectroscopy in simulated body fluid (SBF) solution, respectively. Microstructural development including the size and distribution of the reinforcement particles, and matrix grain size were studied by optical microscopy and scanning electron microscopy (SEM). Mechanical test results revealed an increase of 27% in the ultimate tensile strength. Biocorrosion behavior approved the lower corrosion rate of the composite samples in comparison with unreinforced alloy. Optical micrographs confirmed the effect of reinforcement particles on twinning formation and reduction of composite grain size (175 μm) compared to that of unreinforced alloy (484 μm). SEM observations exhibited the formation of graphene scaffolds and their positive effect on the mechanical and biocorrosion properties.