X-ray tomography investigation of Fe-rich intermetallics in AlSi alloys

Iron exists as a common impurity element in AlSi foundry alloys. The main consequence of the presence or adding of iron to AlSi alloys is the formation Fe-rich intermetallics with especially deleterious β-Al₅FeSi. This work aims to identify the role of fluid flow on the microstructure and intermetallics in Al-9 wt.% Si-0.2/0.5/1.0 wt.% Fe alloys directionally solidified under defined thermal and fluid flow conditions and extensively uses 3D x-ray tomography to get a better insight into their morphology and formation. The results have revealed the growth of larger and more dense β-Al₅FeSi intermetallics in the specimen centre as an effect of forced flow. The reconstructions confirmed that the course of number density at the specimen cross section increases from the specimen edge to its centre.