The Influence of Fluid Flow on Intermetallic Phases in Al-Cast Alloys
Technical Al-Si alloys always contain sufficient amounts of Fe and Mn, especially alloys made from scrap. During casting, Fe-containing intermetallics, such as Al-Fe, Al-Fe-Si and Al-Fe- Mn-Si phases, are formed between the aluminum dendrites. Fe and Mn-rich intermetallic phases are well known to be strongly influential on mechanical properties in Al-Si alloys. In the present work the influence of controlled fluid flow conditions on the morphology and spatial arrangement on intermetallic phases in cast Al-Si alloys is characterized. A binary Al-7wt.%Si and a ternary Al- 7wt.%Si-1wt.%Fe alloy was solidified under and without the influence of a rotating magnetic field (3mT at 50Hz) over a range of solidification velocities (0.015- 0.18mm/s) at a constant temperature gradient G of 3K/mm. The scientific results reached so far indicate a strong influence of the electromagnetic stirring on the primary dendrite and secondary dendrite arm spacings.
W.J. Poole, M.A. Wells and D.J. Lloyd
S. Steinbach, N. Euskirchen, V. T. Witusiewicz, L. Sturz, L. Ratke, "The Influence of Fluid Flow on Intermetallic Phases in Al-Cast Alloys", Materials Science Forum, Vols. 519-521, pp. 1795-1800, 2006