Review of bioresorbable AZ91, AZ31 and Mg–Zn–Ca implants and their manufacturing methods

In this paper, the magnesium alloys, such as AZ91, AZ31 and Mg–Zn–Ca are reviewed for the bioimplants application. A perspective of controlling the high degradation rate of Mg alloys is discussed by alloying, manufacturing methods, surface coating and surface treatment. The major constraint while using magnesium as an implant is the stress-shielding effect, which can be resolved by producing the Mg implant with Young's modulus closer to the cortical bones. The latest development for minimising the stress-shielding effect is by creating a porous magnesium scaffold although a change in fatigue resistance is unavoidable. The influence of manufacturing methods, such as die-casting, powder metallurgy, rolling and additive manufacturing is also discussed on the mechanical strength and degradation behaviour.