Self-protection against corrosion of aged magnesium alloy in simulated physiological environment

A self-protection behavior of Mg – 7.5 Al – 0.8 Zn – 0.2 Mn alloy in cell culture media is reported. Using aging treatment, the β-phases (Mg17Al12) are precipitated from the supersaturated α-phases and distributed along grain boundaries or grains. The aged alloy suffers from severe corrosion in the early immersion stage but after a critical immersion time, its corrosion resistance increases rapidly in the later stage. The mechanism is discussed based on the role transition of β-phase and the precipitation of phosphates by localized basification. Moreover, the aged alloy also exhibits a better biocompatibility.