The Effect of Manganese and Strontium on Iron Intermetallics in Recycled Al-7% Si Alloy

The present work deals with effect of strontium and manganese on modification of iron intermetallics in recycled aluminium-silicon alloys. Al-Si alloys with the addition of 1 and 2% Fe were prepared using casting method. In order to modify the brittle intermetallics, Sr and Mn were added to Al-Si alloys. Result shows that manganese modifies β-Al₅FeSi compounds by transforming the needle-like structure to a script-like morphology. Increasing Mn content to above 0.5 wt%. resulted in the formation of large chunks of α-phase compounds. Most of these large chunks were identified as α-Al₁₅(Fe,Mn)₃Si₂. Further, the addition of strontium showed only a little modification of iron intermetallics, but it modifies silicon particles present in Al-Si alloys, refining their needle-shaped structures. This morphological transformations may be helpful in improvement of tensile properties of the modified Al-7Si cast alloys compared to the unmodified Al-7Si cast alloys.