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Iron is generally regarded as an unavoidable impurity in Al-Si casting alloys.The acicular AI_3Fe andβ-AI_5FeSi(or Al_9Si_2Fe_2) 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 AI-12%Si-2%Fe and AI-2%Fe alloys.The results show that the USF applied to Al-Fe alloys caused the morphological transformation of both primary and eutectic AI_3Fe 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-AI_9Si_2Fe_2 was substituted by star-like α-AI_(12)Si_2Fe_3.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.
Iron is generally considered as an unavoidable impurity in Al-Si casting alloys. The acicular AI_3Fe and β-AI_5FeSi (or Al_9Si_2Fe_2) are common iron-containing intermetallic compounds (IMCs) in conventional structures which have a detrimental impact on the mechanical properties. This paper, ultrasonic field (USF) was applied to modify acicular iron phases in AI-12% Si-2% Fe and AI-2% Fe alloys. results show that the USF applied to Al-Fe alloys caused the morphological transformation of both primary and eutectic AI_3Fe 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. The USF was applied, the acicular β-AI_9Si_2Fe_2 was substituted by star-like α-AI_ (12) Si_2Fe_3. The modification rate of both binary and ternary iron IMCs relates to the USF treatment duration. undercooling induced by the ultrasonic vibration contributes to the nucl eation of intermetallics and can explain the transformation effect.