Study of controllable inclusion addition methods in Al melt

Abstract

Ceramic Foam Filtration (CFF) is a widely used technique to remove inclusions from Al melt. To ensure sufficient inclusions in the melt during the grain refiners/filtration interaction, inclusion addition methods, such as chips addition, powder addition, mechanical stirring, and wet up-gassing have been studied in this work. It is found that the addition of oxide causes the formation of irregularly shaped micropores in the cast samples. Chip addition is simple to conduct, introducing large amount and size of oxide film contamination. The 6061 alloy chips were more helpful for inclusion contamination than that for commercial purity Al chips. This is due to the improved wettability by magnesium (Mg) content in the chips. The addition of oxide powder is difficult due to the poor wetting between oxide and Al matrix. Vortex created by mechanical stirring and pre-treatment of the powders improved the powder addition significantly. Wet up-gassing introduces pores and a large amount of dross based on the flow rate of the Ar gas.