Ultrasound-assisted casting of AZ91D-1.5%Ca – Shifting T4 paradigm for downstream processing

• Mg 17 Al 12 phase is refined using ultrasound during AZ91D-1.5%Ca cooling. • Dissolution rate during T4 is higher for fine and divorced morphologies of Mg 17 Al 12. • T4 optimization of samples treated by acoustic energy helps downstream processing. The effect of the as-cast microstructure on solution treatment of AZ91D-1.5%Ca was investigated. Ultrasound treatment was applied during the casted alloy's cooling, promoting the refinement of α -Mg and β -Mg 17 Al 12 phases. Fine and divorced β -phase was found in the ultrasound-treated sample, resulting in a superior dissolution rate of this intermetallic during subsequent solution treatment. The results indicate that tailoring the as-cast microstructure may be a route for optimizing the solution treatment necessary for downstream plastic deformation processes. The solution treatment's duration and temperature may be decreased, making the process economically and ecologically sustainable.