*2.1. Casting Aluminum Alloy*

The quality and competitiveness of a casting strongly depend on the quality of the molten alloy and the technology used to produce it. Aluminum alloy casting is not an easy process, since these alloys are prone to dendritic and heterogeneous structures, as well as the absorption of hydrogen during melting. Thus, a specific melt processing operation is required in order to reduce and control the level of porosity in the microstructure after solidification. Controlling the microstructure of aluminum alloys is of primary importance to achieve high mechanical performance, requiring suitable degassing, modification, and refinement techniques. Conventional casting is a well-established process for the manufacture of a wide variety of aluminum components. Nevertheless, achievable casting performance is limited due to defects that emerge during melt processing and solidification. In recent years, an effort has been made to develop new and reliable techniques to control the microstructure of several engineering alloys, with a particular emphasis on Al-based alloys, to overcome the problems associated with traditional melt techniques.

The effect of traveling magnetic fields (TMFs) on the grain and micro-pore formation in an Al-Cu alloy was studied by Xu et al. [1]. In this study, it was reported that the forced convection induced by TMF break the dendrites, refine the grain size, and promote liquid feeding, leading to a decrease in the volume fraction of the porosity and improved mechanical property. The microstructural evaluation and corrosion resistance of a semisolid Cast A356 alloy were studied by Gebril et al. [2]. For that, a combination of *as-cast* and semisolid casting using a cooling slope processed by equal channel angular pressing (ECAP) was used. Eskin and Wang [3], Kudryashova et al. [4] and Puga et al. [5] applied the ultrasonic vibration to study the effect of ultrasonic melt treatment in the solidified microstructure of aluminum alloys. The role of the roll-separating force in the high-speed twin-roll casting of aluminum alloys was examined by Kim et al. [6]. For that, a traditional twin-roll casting (TRC) process was designed to combine metal casting and hot rolling into a single operation.
