Revista de ciencias e ingeniería de materiales

Effect of Antimony on the Tensile Strength and the Morphology of Si Platelets in Recycled Aluminum Piston Alloys

Abstract

Durowoju MO, Babatunde IA, Raheem WA and Ajala MT

Recycled AlSi2.4Mg cast alloys can be used directly in new cast products such as textile machinery parts and for structural engineering such as aluminum sidings and window frames. In this work, the modification effect of antimony (Sb) on the microstructure and tensile strength of recycled AlSi2.4Mg cast alloy was systematically investigated. Aluminum Piston scraps was melted in a furnace to form a melt composition. The melt was adjusted to form the present composition, consisting essentially of 2, 4, 6, 8, 10 and 12 gr addition of Sb. However, its effect as a modifier is more pronounce at 8 gr addition of Sb and caused refinement of microstructure, which led to increase in mechanical properties. It was obvious that Sb modify the coarse Si platelets into a more fibrous one. An optimal tensile strength of 82.59 MN/m2 was obtained.
However, fractal analysis performed on the micrograph revealed that the formation and features of Si platelets in as-cast sample and samples treated with 2 to 4 gr of Sb can act as a seedbed for micro-crack initiation because of their irregularity in nature and their departure from perfect shape. The best platelet shape was observed in 8 gr addition of Sb having a weighted average value of fractal dimension D=0.5961 and sphericity β=0.8501 respectively.