Formation of inverse segregation on the surface of belt-cast Al–Fe–Si and Al–Fe–Si–Mn alloys

The surface microstructure of belt-cast Al–Fe–Si and Al–Fe–Si–Mn alloys has been studied. It was found that under some conditions a layer with a high density of intermetallics, an inverse segregation layer, forms on the surface. The mechanism of the formation for these structures was studied. It is suggested that oscillatory changes of the cooling rate and flow of the enriched melt from behind the solidifying shell to the surface cause this inverse segregation to form.