The influence of manufacturing processes on the microstructure and corrosion of the AZ91D magnesium alloy evaluated using a computational image analysis

The influence of different manufacturing processes on the microstructure and corrosion of the AZ91D magnesium alloy was investigated. The twin-roll casting process was compared with an established high-pressure die casting process and the Thixomolding® process. The best corrosion resistance was found in thixomolded specimens due to a continuous and small meshed β-phase network, a homogeneous and small grain size, a minimal extent of Al and Zn segregations and the highest amount of β-phase. Parabolic corrosion-time dependence was found for thixomolded AZ91D and attributed to microstructural features. A computational image analysis was adapted for AZ91D micrographs and utilised for microstructural quantification.