Bio-corrosion impacts on mechanical integrity of ZM21 Mg for orthopaedic implant application processed by equal channel angular pressing

The mechanical integrity of rolled ZM21 Mg was improved by equal channel angular pressing (ECAP) to function as a potential biodegradable bone screw implant. Electron backscattered diffraction (EBSD) revealed deformed grains of 45 mu m observed in rolled ZM21 Mg. They were transformed to equiaxed fine grains of 5.4 mu m after 4(th) pass ECAP. The yield strength of rolled and ECAPed ZM21 Mg alloys were comparable. In contrast, 4(th) pass ZM21 Mg exhibited relatively higher elongation when compared to rolled sample. The mechanical properties of rolled and ECAPed ZM21 Mg were dependant on both grain refinement and crystallographic texture. The rolled and 4(th) pass ECAPed tensile samples exhibited nonlinear deterioration of mechanical properties when tested after 7, 14, 21 and 28 days immersion in Hank's solution. The evaluation signifies that regardless their processing condition, ZM21 Mg alloys are suitable for surgical areas that requires high mechanical strength. In addition, the 4(th) pass ECAP samples were viable to MG-63 cells proving themselves to be promising candidates for future in vivo studies.

Automated summary

The study improved the mechanical properties of ZM21 magnesium through ECAP processing, making it a suitable material for orthopedic implants. Grain refinement and crystallographic texture were found to play a key role in determining the mechanical properties of the processed ZM21 magnesium. The ECAP samples showed biocompatibility with cells, indicating their potential for future in vivo studies.