电流对Al-4．5 Cu合金定向凝固组织的影响.pdfVIP

学兔兔 Jan．2O1O · 22 · VOI．59 NO．1 电流对AI一4．5％Cu合金定向凝固组织的影响 闫 猛，宋长江，张云虎，翟启杰 (上海大学上海市现代冶金及材料制备重点实验室，上海200072) 摘要：为揭示脉冲电流对晶体生长的影响机理，研究了脉冲电流和直流电对AI．4．5％Cu合金定向凝固胞状树枝晶组织 的影响。结果表明：脉冲电流和直流电都能消除二次枝晶臂，减小糊状区深度和宽度，使一次枝晶间距减小；比较而 言，脉冲电流处理的固．液界面较为平直，而直流电使界面变得凸凹起伏。分析认为电流偏聚所形成的热效应导致胞晶 分裂可能是电流影响胞晶一次间距的主要原因，而脉冲电流引起的强制对流使得固一液界面更加平直。 关键词：脉冲电流；直流电；定向凝固；固．液界面 中图分类号：TG146．2 1 文献标识码：A 文章编号：1001—4977(2010)01—0022—04 Infl~Jence of Electric Current On DirectionaI Solidification StruIntlue On cti0naI 0liditicatiOn Struct‘urere Of Al_4．5％Cu AIloy YAN Meng，SONG Changqiang，ZHANG Yun—hu，ZHAI Qi-jie (Shanghai Key Laboratory of Modern＆Material Processing，Shanghai University， Shanghai 200072，China) Abstract：To demonstrate the influence mechanism of the electric current on cystaI growth，the influences of electric current pulse(ECP)and direct current(DC)on cellular-dendritic structure Of AI-4．5％Cu alloy under directional solidification were contrastively studied．The results show that ECP and DC both can eliminate the secondary dendrites，make the mushy zone and the cellular spacing decrease．For the sample treated by ECP，the solid—liquid interface is very planar，while that of samples treated by DC is scraggy．Analysis results suggest that cellular split resulting from Joule heat may be the main reason for decrease of first cellular spacing，and the forced convection caused by ECP make solid-liquid interface more planar． Key words：electric current pulse；direct current；directional solidi