Structural and morphological evolution of Fe–rich phases in Al–xMg–6Si–4Fe alloys

Abstract

In this paper, the influence of Mg content on the evolution of Fe–rich phases in Al– xMg–6Si–4Fe alloys has been investigated. It was found that the Fe–rich phase in Mg–free Al–6Si–4Fe alloy is α–AlFeSi with the chemical formula of Al15Fe3Si2, performing as polyhedral morphology. When the addition of Mg is 2 ​wt% and 4 ​wt%, part of α–AlFeSi particles evolve to flake–like Al13Fe4 phase. With further increase of Mg content to 6 ​wt% and 10 ​wt%, the morphological evolution of Al13Fe4 from flake–like to petal–like with ten branches was detected. The evolution mechanisms were supposed relating to the combination tendency between Mg and Si atoms and the enhanced undercooling level caused by Mg addition.