Effect of Fe, Mn Content on the Castability in Al-9wt%Si-Mg System Alloys for High Elongation

Effect of Fe and Mn contents on the castability of Al-9wt%Si-xMg-yFe-zMn alloy has been studied. The alloy was composed of α-Al phase, Al+eutectic Si phase, β-Al5FeSi compound and chinese script α-Al15(Mn,Fe)3Si2 compound. β-Al5FeSi and αAl15(Mn,Fe)3Si2 compounds assumed to effect the fluidity and shrinkage behaviors of the alloy during solidification due to the crystallization of α-Al15(Fe,Mn)3Si2 and β-Al5FeSi compounds above eutectic temperature. As Fe and Mn contents of Al-9wt%Si0.3wt%Mg system alloy increased from 0.15wt% to 0.6wt% and from 0.3wt% to 0.7wt%, fluidity of the alloy decreased by 5.7% and 3.3%, respectively. And as Mg content of Al-9wt%Si-0.45wt%Fe-0.5wt%Mn system alloy increased from 0.3wt% to 0.4wt%, fluidity of the alloy decreased by 8.6%. When Fe content of the alloy increased from 0.15wt% to 0.6wt%, macro shrinkage ratio decreased from 6.1% to 4.1%, and micro shrinkage ratio increased from 0.04% to 0.24%. Similarly, Mn content of the alloy increased from 0.3wt% to 0.7wt%, macro shrinkage ratio decreased from 6.0% to 4.5% and micro shrinkage ratio increased from 0.12% to 0.18%. Judging from the castability of the alloy, Al-9wt%Si-0.3wt%Mg alloy with low content of Fe and Mn, 0.1wt% Fe and 0.3wt% Mn, is recommendable.