The Effect of Hot Extrusion on Microstructure and Hardness of Zn-۵Cu-Mn-AgBiodegradable Alloy

Zinc is one of the most promising biodegradable metals, along with magnesium and iron. Zinc appears toovercome some fundamental problems associated with Mg and Fe (high and prolonged degradation rates,respectively) in biomedical applications and non-biodegradable metals (inflammation, allergic reactions, andexcessive wear). However, the main challenge ahead regarding zinc metal is its poor mechanical properties.Therefore, the mechanical properties of zinc alloys can be increased by adding alloying elements or usingthermomechanical techniques to modify the grain size, such as extrusion.This research used the casting method to prepare Zn-۵Cu-Mn-Ag alloy (Wt%). Copper, manganese, and silveralloy elements increased hardness and malleability and created antibacterial properties. In order to modify themicrostructure and improve the properties of the alloy, the secondary process of hot extrusion was applied.Finally, some common tests were used to check the alloy's microstructure and properties. The results of XRDanalysis showed that the above alloy has four phases of pure zinc, CuZn۵, MnZn۱۳, and Zn۳Ag. Afterhomogenization, MnZn۱۳ secondary phase particles were dissolved mainly in the zinc background. After thesecondary process of hot extrusion, the secondary phase particles were broken and spread throughout thestructure. Also, dynamic recrystallization occurred, and grains were modified. According to the hardness test,due to the presence of CuZn۵ hard secondary phase particles, the hardness increased compared to pure zinc.The extruded alloy seems to be a promising candidate for a wide range of biodegradable implant applications.