Retardation of surface corrosion of biodegradable magnesium-based materials by aluminum ion implantation

Aluminum ion implantation is employed to modify pure Mg as well as AZ31 and AZ91 magnesium alloys and their surface degradation behavior in simulated body fluids is studied. Polarization tests performed in conjunction with scanning electron microscopy (SEM) reveal that the surface corrosion resistance after Al ion implantation is improved appreciably. This enhancement can be attributed to the formation of a gradient surface structure with a gradual transition from an Al-rich oxide layer to Al-rich metal layer. Compared to the high Al-content magnesium alloy (AZ91), a larger reduction in the degradation rate is achieved from pure magnesium and AZ31. Our results reveal that the surface corrosion resistance of Mg alloys with no or low Al content can be improved by Al ion implantation.

► Al ion implantation retards the surface bio-corrosion of pure Mg as well as AZ31 and AZ91 Mg alloys. ► Good initial corrosion resistance can be achieved in an Mg alloy with a low total content of Al. ► Al ion implantation produces a new oxide/metal surface gradient structure.