Synthesis and Characterization of Magnesium Alloy Surface Composite (AZ91D - SiO2) by Friction Stir Processing for Bioimplants

Magnesium shows potential for bioimplant applications because of its high biocompatibility and equivalent bone strength. However, the high corrosion rate of magnesium and magnesium alloys in the physiological environment results in the rapid evolution of H 2 gas, which is lethal to the neighboring tissues. With an intention to reduce the corrosion rate, magnesium alloy AZ91D is reinforced with nanophase SiO 2 to fabricate surface composite by friction stir processing. The metallurgical characterization reveals the refinement of grains, fine dispersion of β phase and nanophase SiO 2 in the composite matrix. The surface characterization of the corrosion products depicts the formation of an adherent layer of corrosion products that are rich in calcium hydroxyapatite and calcium-magnesium phosphate. The combined consequence of metallurgical and corrosion phenomenon reduces the corrosion rate, aids bone growth, and augments implant-bone integration. The results demonstrate that AZ91D-SiO 2 composite is an effective material for bioimplant applications. Graphical Abstract AZ91D-SiO 2 surface composite for bioimplant applications