【作者】 李会玲；

【导师】 曾建民；

【作者基本信息】 广西大学 ， 材料加工工程， 2006， 硕士

【摘要】 变质处理是提高铝—硅合金机械性能的重要手段之一。目前生产上所要用的变质剂主要是钠盐和锶。Sb作为一种长效变质剂在理论和实践上还不够成熟，在生产中还没有被广泛应用。因此有必要对Sb在铝硅合金中的作用做更深入的研究。本文采用差热分析，扫描电子显微镜及电子探针分析等方法研究了Sb元素对铸造铝硅合金的变质和细化问题，并利用图像分析方法，对各种缺陷和变质效果进行定量分析，提高了产品检测的速度和准确度。 实验结果表明：（1）在较快的冷却速度下，0.2％的Sb含量对ZL114合金产生了良好的变质效果。变质良好时，合金的的凝固温度，共晶温度降低，α（Al）相析出潜热减小，共晶Si相结晶潜热增大。（2）对于砂型铸造，Sb元素对ZL114合金也起到了一定的变质作用。（3）在不含镁元素的情况下，变质组织随着Sb含量的增加逐渐细化，当含量超过2％后，组织又开始变粗大。（4）在含0.5％Mg的情况下，0.2％Sb在快冷条件下的变质效果最好，而含0.6％Sb的合金变质效果变差。当Sb含量达到2％的时候，合金组织又变得很细小（5）在冷却速度较慢的情况下，随着Sb含量的增加，针孔度增加，而在冷却速度较快的情况下，合金针孔度对锑含量不敏感。（6）Sb在合金中以AlSb和Mg₃Sb₂的形式存在。高熔点AlSb的存在促使α（Al）相析出，AlSb在结晶前沿的聚集，造成共晶过冷度增加，更多还原

【Abstract】 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更多还原