The poisoning effect of Sc or Zr in grain refinement of Al-Si-Mg alloy with Al-Ti-B

Abstract The effects of Sc or Zr on the grains of Al-Si-Mg alloy with Al-Ti-B addition were investigated under sand casting conditions by a polarizing microscope, differential scanning calorimetry and scanning electron microscopy. The results showed that the order of grain size is Alloy 1 (A357)   Alloy 3 > Alloy 2. In Al-Si-Mg alloy with Ti-B, with added Sc or Zr, many intermetallic compounds containing Sc and Ti or Zr and Ti appeared, which meant that the content of Ti as nucleation cores in the melt decreased, and the poisoning occurred in the nucleation stage of grains.