Effect of Iron in Al-Mg-Si-Mn Ductile Diecast Alloy

The effect of iron on the micro structure and mechanical properties of Al-Mg-Si-Mn alloys has been investigated in high pressure diecast components in association with CALPHAD modelling of the multi-component Al-Mg-Si-Mn-Fe system. It is found that the Fe-rich intermetallic phases solidify in two stages in the high pressure die casting process: one is in the shot sleeve and the other is in the die cavity, showing different morphologies. The compact and star-like intermetallics are identified as α-AlFeMnSi phase with typical composition of Al12(Fe,Mn)3Si. At the increased level of Fe content, β-AlFe is found in the micro structure with a long needle-shaped morphology, which is identified as Al13(Fe,Mn)4Si0.25. The existence of Fe-rich intermetallics in the alloy slightly increases the yield strength, but significantly reduces the elongation. The ultimate tensile strength maintains at similar levels when Fe contents are less than 0.6wt.%, but decreases significantly with the further increased Fe concentration in the alloys.