熔剂净化对Al－4．5wt％Cu合金过冷及组织的影响

The Effect of Flux Refining on Undercooling and Structure of Al-4.5wt%Cu Alloy

采用盐类熔剂对大体积Ａｌ－４．５ｗｔ％Ｃｕ合金进行净化处理，研究了熔剂净化对Ａｌ－４．５ｗｔ％Ｃｕ合金过冷及组织的影响。通过大量的实验研究证明：粘性熔剂更能有效地去除合金中的异质核心，使合金获得较大的过冷度；随着过冷度的增大，合金的宏观组织由细小的等轴晶逐渐过渡到粗大的柱状晶，其临界转变过冷度为４０℃；二次枝晶间距随过冷度的增大而增大，其转变过冷度为５０℃。

The bulk Al-4.5wt%Cu alloy has been refined by the salt-flux and the effects of flux refining on the undercooling and the structure of the alloy have been studied. The results show that the sticky flux can get effectively rid of the heterogenous nucleuses in the mett and make the alloy obtain lower undercooling. The macrostructure of the samples varied gradually from fine equiaxed grains to coarse columnar grains with undercooling degree increasing. The critical undercooling degree is 40℃. The second dendrite arm spacing also increases with undercooling degree increasing. The undercooling degree of transformation is 50℃ for the second dendritic crystal.