Modification of Al-11.1Si alloy with sodium through casting route

In-spite of many advantages of Al-Si alloys, it is limited in industrial application due to lack of ductility, because microstructure contains plate like Si particles which is embedded in an Al-matrix. This article describes the modification effect on microstructure and mechanical properties of sodium modified hypoeutectic Al-Si alloys. Modification has been done by using pure Na as modifier with different composition 0.08, 0.12 and 0.16 wt% at 10, 15 and 20 min holding time on hypoeutectic Al-Si alloy. Microstructure of modified samples has been analyzed by optical microscope and eutectic particle size was measured by using ImageJ software. In all cases the modified microstructure has shown the fine fibrous eutectic particle which is uniformly distributed throughout the sample. Tensile and hardness test were carried out by tensometer and Vickers hardness testing machine and the properties were studied. The fracture surface analysis was carried out by SEM. Due to modification, eutectic particle size has reduced and mechanical properties have improved.