Al-4.5％Cu合金的过冷及凝固组织特征

UNDERCOOLING AND STRUCTURE OF Al-4.5%Cu Alloy

对Ａｌ－４．５％Ｃｕ合金在纯石黑坩埚中用卤盐熔剂净化后的过冷度及其在金属锭模中的凝固组织特征进行了研究。实验结果发现：粘度较大的半固态熔剂对合金的净化作用较强，可使合金在金属锭模中得到６２℃的形核过冷度；金属熔体净化得到的热力学过冷度对合金形核及最终宏观组织的影响明显不同于激冷得到的动力学过冷度对其所产生的影响，在一定过冷度下。

The undercooling and structure of the Al-4 5%Cu alloy denucleated by the chloride flux in a fine graphite crucible is studied in this paper. It is found that the viscous flux is of a strong denucleation to the alloy and makes the alloy undercool by up to 62℃ in a metal mold. The influence on the alloys nucleation and strucutre of the thermodynamic undercooling abtained by denculeating is different from that of the dynamic undercooling obtained by quenching in low undercooling. The crystal-size increases with the thermodynamic undercooling in a certain undercooling.