Refinement of Al-Si eutectic grains - A novel method to produce high integrity Al-Si alloy castings

Eutectic modification with Sr, Na or Sb yields a refined fibrous silicon morphology which can improve the tensile ductility of cast Al-Si alloys. However, many companies choose not to use modifiers due to increased scrap rates and negligible beneficial effects on the mechanical properties because of alterations in the porosity characteristics of the castings. Here we report a novel method to modify Al-Si alloys which reduces the porosity of the castings while maintaining the well-modified silicon structure, thus producing consistent high performance Al-Si alloy castings. This new invention is based on the grain refinement of the Al-Si eutectic grains, or cells.