高密度脉冲电流对过共晶Al-Si合金凝固组织的影响

研究了高密度脉冲电流对过共晶Al 19Si合金凝固组织的影响。结果表明 :未经任何处理的试样凝固组织中含有大量的长杆状初生Si,其长宽比较大 ,且共晶Si尺寸较大 ;而经过高密度脉冲电流处理后 ,凝固组织中初生Si转变为块状 ,长宽比显著减小 ,共晶Si呈短杆状 ,尺寸较小 ,另外在试样的局部存在初生Si晶粒破碎现象 ,这是高密度脉冲电流在熔体内部产生不平衡的电磁力而导致不平衡剪切的结果

Effect of high density pulse current on solidification structure of hypereutectic Al-19Si alloy

The influence of high density pulse electric current(HDPEC) on the solidification structure of hypereutectic Al 19Si alloy was studied. The results show that there exist lots of primary Si phases with long pole shape in the solidification structure when the specimen are not treated by HDPEC, and the aspect ratio of Si grain is larger. The size of eutectic Si is large. However, through HOPEC, the morphology of the primary Si phases changes into blocky structure greatly, and the aspect ratio of Si grain becomes smaller. The eutectic Si phases appear short pole, and the size of them decreases obviously. Moreover, there exist some smallest and broken Si grains in certain area of the specimen, which is resulted from the non equilibrium distribution of the electric magnetic force existed in the melt.