The Behavior Of Antimony In Al-Si Casting Alloys

Modification is one of the most important methods to improve the mechanical properties of Al-Si alloys. At present, sodium salt and strontium are commonly used modifier in practice. Antimony, as a permanent modifier is not extensive used because of its inexperience. So the effects of antimony on Al-Si alloys need to be further studied. In this paper, antimony effects of modification and grain refinement on Al —Si cast alloys have been studied by using thermal analysis of differential scanning calorimeter, scanning electron microcopy and electron probing analysis. Image automatic analyzer has also been applied to quantitatively analyze the pinhole degree and modification effect, which advances the speed and accuracy of product test.The results showed that: (1) 0. 2% Antimony exerted good modification impact on ZL114 alloy at rapid cooling rate. When best modification obtained, the freezing point and eutectic temperature droped down, while the crystal latent heat of α (Al) and Si phases decreased and increased respectively. (2) Antimony could also modify ZL114 alloy in sand mold. (3) When magnesium didn' t exist in the Al-Si alloys, the modification structure became finely at first with the increasing of antimony content, while the structure would grow bigger gradually after antimony yielded about 2%. (4) When 0.5% magnesium existed in the Al-Si alloys, the modification effects by 0. 2% antimony were perfect at quick cooling rate, and the modification effects by 0. 6% antimony were weakened. Modification structure wouldn' t become finely any more until 2% antimony was gained. (5) Pinhole degree was more serious with the increasing of antimony content at the slow cooling rate, while at the rapid cooling rate, pinhole degree was not influenced by antimony content; (6) Antimony existed in alloys as the...