Thermal Characteristics, Mechanical Properties, In Vitro Degradation and Cytotoxicity of Novel Biodegradable Zn-Al-Mg and Zn-Al-Mg-xBi Alloys

Ternary Zn-0.5Al-0.5Mg and quaternary Zn-0.5Al-0.5Mg-xBi (x = 0.1, 0.3 and 0.5) alloys were studied to evaluate the thermal and structural characteristics, mechanical properties, cytotoxicity and in vitro degradation behavior. Thermal analysis and microstructural observations showed that Zn-0.5Al-0.5Mg is composed of FCC-Al ? HCPZn + Mg-2(Zn, Al) 11 while a new phase a-Mg3Bi2 appeared after the addition of Bi to the Zn-0.5Al-0.5Mg ternary alloy. The results revealed that the quaternary Zn-Al-Mg-Bi alloys have higher tensile strength, elongation and hardness but slightly lower corrosion resistance than those of the ternary Zn-Al-Mg alloy. Based on the MTT assay, the Zn-Al-Mg and Zn-Al-Mg-Bi alloys were found to be biocompatible, and thus, they can be considered for further investigation in an in vivo environment.