The present study investigates Mg-2Zn-1Ca/XMn alloys as biodegradable implants for orthopedic fracture fixation applications. The effect of the presence and progressive addition of manganese (X = 0.3, 0.5, and 0.7 wt.%) on the degradation, and post-corrosion compressive response were investigated. Results suggest that the addition of manganese at 0.5 wt.% improved the corrosion resistance of Mg-2Zn-1Ca alloys. The pH values stabilized for the 0.5Mn-containing alloy and displayed a lower corrosion rate when compared to other Mg-2Zn-1Ca/Mn alloys. Mg-2Zn-1Ca showed a progressive reduction in the compressive strength properties at the end of day 21 whereas Mg-2Zn-1Ca/0.3Mn and Mg-2Zn-1Ca/0.5Mn samples showed a decrease until day 14 and stabilized around the same strength range after day 21. The ability of Mg-2Zn-1Ca/0.5Mn alloy to develop a network of protective hydroxide and phosphate layers has resulted in the corrosion control of the alloy. Mg-2Zn-1Ca/0.7Mn displays segregation of Mn particles at the grain boundaries resulting in decreased corrosion protection. The mechanism behind the corrosion protection of Mg-2Zn-1Ca alloys was discussed.
Keywords: biodegradable implants; corrosion; hank’s balanced salt solution; magnesium alloy; manganese; mechanical strength.