冷速对Al-4.29Cu-1.09Mg合金凝固组织的影响

Effect of Cooling Rate on Solidification Microstructures of Al-4.29Cu-1.09Mg Alloy

选取Al-4.29Cu-1.09Mg合金,采用石墨型、砂型、保温材料等3种铸型进行了凝固试验,采用扫描电镜、能谱分析等手段研究了不同冷速铸锭的凝固相组成与形貌、硬度、二次枝晶间距等。结果表明,随着冷却速率的提高,合金凝固组织的二次枝晶臂间距明显减小,硬度增大。在二次枝晶臂尺度范围内,砂型铸锭中Cu和Mg元素出现了明显的微观偏析,枝晶臂边缘成分明显高于枝晶臂中心,并发现Cu元素的偏析程度要大于Mg。

Solidification experiments were carried out using ternary alloy Al-4.29Cu-1.09Mg with three different kinds of materials, graphite, sand, and insulated material. The solidification phase types and morphologies, the hardness, the secondary dendrite arm spacing were investigated by scanning electron microscopy and component analysis. The results show that the grain size and second dendrite arm space of the ingot are decrease, and the hardness is increased with the increase of solidification rate. In the second dendrite arm scale, microsegregation of element Cu and Mg can be observed in the sand mold sample. The solute composition at the edge of the second dendrite arm is higher than that at the center, and the degree of microsegregation of Cu is larger than Mg.