Three Dimensional Morphology of Mn Rich Intermetallics in AlSi Alloys Investigated with X-Ray Tomography

Abstract

Elementary Mn has a great importance as neutralizer of Fe intermetallics like β-Al5FeSi, which have detrimental effect on mechanical characteristics of AlSi alloys. Presence of Mn in AlSi alloys causes the formation of other intermetallic phases. To understand the effect of solidification conditions and fluid flow on the microstructure of AlSi-based alloys and the addition of Mn leading to Mn-based intermetallics, Al-5 wt pct Si 0.2/0.4/1.0 wt pct Mn alloys have been directionally solidified under defined thermal (gradient 3 K/mm, solidification velocity 0.02-0.12 mm/s) and fluid flow (rotating magnetic field 6 mT) conditions. The primary Al-phase and Mn-based intermetallic phases were studied using 3D X-ray tomography. The spatial morphology of primary phase and intermetallics were characterized with respect to different fluid flow and solidification conditions. The tomography has showed the 3D complicated structure of Mn phases developed.