Magnesium (Mg) alloys are widely used in biomedical applications thanks to their combination of exceptional mechanical properties, biocompatibility, and biodegradability. Mg-ZK alloy series; for instance, ZK40, ZK60 and ZK61; is an example of the most commonly used Mg bio-alloy. Zirconium (Zr) acts as a grain refiner when added to Mg, which manipulates the material structure by producing a refined internal structure and enhancing its properties. In addition, when Zinc (Zn) is added to a Mg-Zr alloy, strength is improved. Therefore, given the favorable properties of ZK alloys in biomedical applications, the current research aimed for the fabrication and the evaluation of a new ZK alloy with a new composition; ZK50, as a potential biomaterial for biomedical applications. Three stages were implemented in order to achieve the objective of this study. In the first stage, ball milling process was used to synthesize nanostructured Mg-ZK50 alloy from elemental powders (Mg, Zr, and Zn). The produced powders (BM) were studied using SEM, XRD and TEM to determine the internal structure refinement as well as the phase development due to milling. In the second stage, Powder-in-Tube (PIT) rolling process followed by annealing was applied to produce consolidated thin sheets from the BM powders. Accordingly, in the third stage, the effect of annealing on the internal structure, mechanical properties, corrosion behavior and cytotoxicity was evaluated. The mechanical milling of the elemental powders produced a nanostructured alloyed powder after 45 hrs of milling with a crystallite size of 8.83 nm, which is considered the finest internal structure for Mg and Mg based alloys to date. Afterwards, nanostructured thin sheets were successfully produced using PIT at 300 Â°C with 67% reduction percent. The modulus of the sheets was found matching to that of human bones. It is worthy to note that annealing was found to have a detrimental effect on the corrosion behavior of the alloy. However, a hydroxyapatite layer was formed which indicated that the produced sheets induced osteoinductivity of the bone. Moreover, cytotoxicity of the sheets was not affected by the sheets and all the produced sheets showed an acceptable toxicity level within the cells. In conclusion, the produced Mg-ZK50 nanostructured alloyed sheets are considered a new potential biomaterial for orthopedic implants that induces osteoinductivity and prevent stress shielding.
MS in Nanotechnology
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(2018).Nanostructured Mg-ZK50 Sheets Fabricated for Potential Use for Biomedical Applications [Master's Thesis, the American University in Cairo]. AUC Knowledge Fountain.
Morcos, Peter Mabrouk. Nanostructured Mg-ZK50 Sheets Fabricated for Potential Use for Biomedical Applications. 2018. American University in Cairo, Master's Thesis. AUC Knowledge Fountain.