电脉冲处理对Sn-15%Pb合金凝固组织中枝晶形态的影响

Effect of derect pulse modification process on solidification structure of Sn-15%Pb Alloy

研究了电脉冲处理对Sn-15％Pb合金凝固组织的影响.通过对Sn-15％Pb合金熔体 施加电脉冲处理,其凝固组织发生了由原始的树枝晶向球状组织的转化,同时晶粒发生明显 细化.分析认为,由于电脉冲处理作用,合金熔体结构发生了改变,使熔体中Pb的活度提高, 进而引起溶质平衡分配系数的变化,导致凝固前沿的溶质富集减轻,溶质分布情况发生改变, 促使树枝晶向球状组织转化,并且使凝固组织发生细化.

The influence of electric pulse modification (EPM) process on the solidification structure of Sn-15% Pb alloy was experimentally investigated. It was shown that after the molten alloy was treated by electric pulse the solidification structure changed from dendrite shape to cellular shape, and the grains were obviously fined. The mechanism of the change in solidification structure by EPM was discussed. The results indicated that EPM process makes the liquid structure of the alloy change: The activity of Pb in the molten Sn-Pb alloy increases, the distribution coefficient tends to 1, the solute enrichment in front of the solid-liquid interface decreases, and the solute distribution changes. All these lead to the change of solidification structure from dendrite to cellular.