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Iron is generally regarded as an unavoidable impurity in Al-Si casting alloys. The acicular Al3Fe and β-Al5FeSi (or Al9Si2Fe2) are common iron-containing intermetallic compounds (IMCs) in conventional structure which have a detrimental impact on the mechanical properties. In this paper, ultrasonic field (USF) was applied to modify acicular iron phases in Al-12%Si-2%Fe and Al-2%Fe alloys. The results show that the USF applied to Al-Fe alloys caused the morphological transformation of both primary and eutectic Al3Fe from acicular to blocky and granular without changes in their composition. In the case of Al-Si-Fe alloys, ultrasonic treatment led to both morphological and compositional conversion of the ternary iron IMCs. When the USF was applied, the acicular β-Al9Si2Fe2 was substituted by star-like α-Al12Si2Fe3. The modification rate of both binary and ternary iron IMCs relates to the USF treatment duration. The undercooling induced by the ultrasonic vibration contributes to the nucleation of intermetallics and can explain the transformation effect.

The solid-liquid method was used to prepare the continuous casting of copper cladding aluminium by liquid aluminum alloy and solid copper, and the interfacial phase formation of Al-Cu bimetal at different pouring temperatures (700, 750, 800 °C) was investigated by means of metallograph, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods. The results showed that the pouring temperature of aluminum melt had an important influence on the element diffusion of Cu from the solid Cu to Al alloy melt and the reactions between Al and Cu, as well as the morphology of the Al-Cu interface. When the pouring temperature was 800 °C, there were abundant Al-Cu intermetallic compounds (IMCs) near the interface. However, a lower pouring temperature (700 °C) resulted in the formation of cavities which was detrimental to the bonding and mechanical properties. Under the conditions in this study, the good metallurgical bonding of Al-Cu was achieved at a pouring temperature of 750 °C. [ABSTRACT FROM AUTHOR]