Solidification behaviour of an AA5754 Al alloy ingot cast with high impurity content

Abstract

AbstractIn view of the recycling of aluminium scrap for automotive sheet application, we have investigated the solidification behaviour of AA5754 alloy containing additional amounts of impurity elements such as Si, Fe, and Cu. Ingot casts with a high impurity content resulted in coarse α-Al dendrites and complex-shaped secondary phases. A large volume of coarse Chinese script and needle-type Fe-bearing intermetallic phases were observed to form at the centre of an ingot. In addition to the grain-boundary eutectic, spherically shaped rosette-type eutectic phases were observed within the Al grain in the high-impurity alloy. The more uniform size distribution of the Fe-bearing intermetallics observed in the Al–Ti–B grain refined alloy is attributed to the presence of a large fraction of α-Al grain boundaries which distributes the eutectic liquid where the Fe-bearing intermetallic forced to nucleate and grow.