Influence of melt treatment of AZ91D alloy on phase morphology and corrosion behaviour in Hank's solution

Abstract

The AZ91D magnesium alloy was processed with the addition of chemical refinement Al5Ti1B or through ultrasonic melt treatment technique. This paper studies the relationship between the corrosion behaviour and the phase's morphology of the produced samples. Electrochemical impedance spectroscopy was carried out in Hank's solution at 37°C for the assessment of corrosion resistance, demonstrating that this property is heavily affected by the change in morphology provided by the applied methods. Correlation analysis suggests that small concave boundaries of the coarser β-Mg phase have a greater impact on corrosion behaviour rather than the reduction in β-Mg volume fraction or the overall homogenisation of the morphology.