ABSTRACT
This chapter provides an overview of two casting processes, and describes how the processing conditions affect intermetallic selection. Industry has been looking for an alternative to conventional direct chill (DC) casting for the production of strip and sheet products. There is considerable interest in by-passing the downstream hot rolling stages and directly casting strip to near-gauge dimensions. The growth velocities and cooling rates in both DC and twin roll casting lead to several non-equilibrium effects, including the extension of solute solid solubility and the formation of new metastable intermetallic phases, with these effects being more marked the more rapid the solidification. A wide range of equilibrium and metastable intermetallic phases have been observed in most as-cast wrought aluminium alloys resulting from the non-equilibrium nature of solidification during commercial processing. Varying solidification conditions can lead to variations in intermetallic phase content at different positions in the casting.
