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通过实验研究了AlSi1铸锭反偏析现象。采用真空感应炉熔炼、石墨模铸造获得高纯AlSi1合金铸锭。利用电感耦合等离子体发射光谱仪分析铸锭中Si成分分布,采用间隙气体分析法分析铸锭气体含量,使用光学显微镜观察了铸锭金相组织。研究发现,铸锭含气量非常低的情况下,铸锭底部、中部和顶部的截面圆内都存在着明显的反偏析,铸锭中部心部区域的Si含量最低。铸锭的边部为尺寸较小的柱状晶,中部为粗大的柱状晶,细小Si析出相弥散分布,心部为等轴晶,Si析出相主要聚集在晶界附近,呈棒状,且尺寸明显长大。AlSi1熔体凝固时,先析出相Si的不断形核与长大消耗大量的Si,使得后凝固熔体贫Si,从而导致了铸锭的反偏析缺陷。
The anti-segregation phenomenon of AlSi1 ingot was studied experimentally. Vacuum induction furnace melting, graphite mold casting obtained high purity AlSi1 alloy ingot. The composition of Si in the ingot was analyzed by inductively coupled plasma atomic emission spectrometer. The gas content in the ingot was analyzed by gap gas analysis. The microstructure of ingot was observed by optical microscope. The results show that there is obvious reverse segregation in the ingot ingot at the bottom, middle and top of the ingot, and the Si content in the middle part of the ingot is the lowest when the ingot gas content is very low. The edge of the ingot is a small columnar crystal, while the middle is coarse columnar crystal. The fine Si precipitates are dispersed and the heart is equiaxed. The Si precipitates mainly gather in the vicinity of the grain boundaries, and the sizes are obvious grow up. AlSi1 melt solidification, the first precipitation of phase Si continuous nucleation and growth consume a large amount of Si, making post-solidification melt Si-poor, resulting in ingot reverse segregation defects.