The mushy zone: Understanding the role of permeability

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Light metals usage in the automotive industry continues to increase with the demand for improved fuel economy and performance through weight savings. Cast products have shown good market penetration by replacing ferrous based components such as cylinder heads and through part consolidation. While light metals usage may advance vehicle energy efficiency, continuous improvement is needed in the upstream processes to increase yield and production energy efficiency. The development of strategies to eliminate casting defects has historically been a trial and error process, but in recent years, the advent of increased computational capabilities, has led to the use of computers to model casting operations and provide quantitative knowledge of casting systems. One of the main difficulties in developing comprehensive quantitative models of casting processes is describing the link between micro and macro scale phenomena. Mushy zone permeability is a good example of this challenge as the coupling between mushy zone microstructure and the resistance to flow continues to be investigated.  The proposed research program is focused on developing new fundamental knowledge on the role that permeability plays in defining the mushy zone. In order to achieve this objective, the program will combine experimental determination of permeability in an industrially relevant alloy with mathematical modeling of fluid flow at the scale of the microstructure. The knowledge gained from the physical testing and modeling will be used to investigate the impact of permeability description on the mushy zone in real castings.