Fe Bearing Intermetallic Phase Formation in a Wrought Al–Mg–Si Alloy

This paper investigates the two dimensional (2D) and three dimensional (3D) morphologies of the Fe bearing intermetallics that forms during the direct chill casting of an AA6063 Al alloy. An intermetallic phase extraction technique was used to facilitate 3D interconnectivity, morphology and fraction of intermetallics. Metallographic 2D analyses suggest the presence of Chinese-script-type and needle-type morphology Fe bearing intermetallics typically at the primary Al grain boundaries, whereas 3D analyse of the extracted intermetallics suggests those particles have dendrite-type and platelet-type morphologies. In-addition, globular shaped intermetallics which were observed in 2D within the primary Al grains where observed to have sphere shaped rosette-type morphology in 3D. α c -AlFeSi and β-AlFeSi were the two dominant intermetallic phases observed in the as-cast billet. Clusters of Ti rich particles were observed at the point from which growth appears to have started suggesting a possible nucleating site for the Fe intermetallics to form during solidification.