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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。
Al-4.29Cu-1.09Mg alloy was selected and the solidification tests were carried out on three kinds of molds, graphite type, sand type and thermal insulation material. The composition and shape of the solidified phases of different cold-speed ingots were studied by scanning electron microscopy and energy spectrum analysis. Appearance, hardness, secondary dendrite spacing and so on. The results show that with the increase of cooling rate, the secondary dendrite arm spacing of the solidified microstructure decreases obviously and the hardness increases. In the range of secondary dendrite arm, the microstructure of Cu and Mg in the sand ingot showed obvious microsegregation. The edge component of dendrite arm was obviously higher than that of dendrite arm. It was found that the degree of segregation of Cu element was greater than that of Mg.