Investigations on the corrosion behaviour and biocompatibility of magnesium alloy surface composites AZ91D-ZrO2 fabricated by friction stir processing

In the current study, friction stir processing was applied as a methodology to produce surface composites of AZ91D magnesium alloy with ZrO2 particles. Microstructural evolution, microhardness profile and corrosion behaviour of the developed surface composite were analysed. The results indicate that the combined effect of friction stir processing and reinforcement of ZrO2 reduced the grain size, and fragmented and dispersed the secondary phases. The fine dispersion of ZrO2 particles contributed to the enhancement of cumulative surface potential, and hence the corrosion resistance of the developed surface composite. The analysis of post-corrosion test specimens revealed the formation of corrosion products that had similar composition to that of hydroxyapatite. The formation of such corrosion products is beneficial, as it contributes to corrosion resistance (stable and adherent layer) and biocompatibility.