Al－4％CU铸锭凝固中自由等轴晶的迁移行为及对宏观偏析的影响

Movement Behavior of Equiaxial Dendrites in Solidifying Al-4% Cu Ingots and Influence on Macrosegregation

研究了Ａｌ—４％ＣＵ合金铸锭在砂型中的缓冷凝固行为，测定了凝固铸锭中的晶粒度和宏观成分分布。研究结果表明，由于Ａｌ—Ｃｕ合金的非平衡凝固行为和固相密度与晶间液相密度差的逆转特性，以及液相成分的重力偏析，引起铸锭中上部等轴晶密度增加并产生明显的逆偏析。

The slow-cooling solidification of Al-4%Cu alloy ingots in sand molds was studied and the grain size and distribution of macrocomposition in the solidified ingots wasalso determined. 'The experimental results show that the density of eguiaxial dendritesin mid-upper central region of the solidified ingots was increased and the obvious neqative segregation was observed, owing to the nonequilibrium crystallization and the reverse change of the density difference between the solid and liquid phases of a solidifiedAl-4%Cu alloy and the gravith segregation in the interdendritic liquid phase.