Development of liquid metal process using local imposition of electromagnetic vibration

用电磁场和交流电同时施加局部振荡的方法对锡铅合金进行了凝固处理，以控制凝固组织。在仅施加静磁场的情况下，由于没有振动而获得粗大的晶粒，而在电流和磁场同时施加的情况下，整个观察区域的组织完全细化。该方法具有细化凝固组织的作用，并对该工艺的细化机理进行了实验研究。通过改变电磁振动作用于试件的周期，考察了组织的细化周期，确定其为凝固的初始阶段。通过在样品中插入不锈钢丝网来指定精炼区域位于电极周围，而与电极的插入位置无关。对流是由电磁振动引起的，因为振动在样品中被激发后，样品中的温差就会急剧减小。根据这些实验结果，推测这一过程的机理是在凝固初期，电磁振动切断了电极周围的枝晶尖端，并通过电磁振动诱导的对流扩散到整个样品区域。此外，强烈的电磁振动也会诱发成核。

A Sn-Pb alloy has been solidified by using an electromagnetic method in which oscillation was locally imposed by a simultaneous imposition of a static magnetic field and an alternating current to control the solidified structures. In the case that only the static magnetic field was imposed, coarse grains were obtained due to no vibration, while in the case of the simultaneous imposition of the electrical current and the magnetic field, the structure was completely refined in the whole observed area. Then, this method has a refining function of the solidified structure.Furthermore, refining mechanism of this process has been experimentally examined. The refining period of the structure was examined by changing the imposing period of the electromagnetic vibration on the sample and it was confirmed as the initial stage of solidification. The refining region was specified to be around the electrodes by inserting a stainless steel wire net in the sample while it was independent of the inserting position of the electrodes. Convection was induced by the electromagnetic vibration because temperature difference in the sample drastically decreased as soon as the vibration was excited in the sample. From these experimental results, the estimated mechanism in this process is that dendrite tips around the electrodes are cut off by the electromagnetic vibration in the initial stage of the solidification and it spread to the whole area of the sample by the convection induced by the electromagnetic vibration. In addition, nucleation is induced by an intense electromagnetic vibration.