关键词: ZL201合金, 电磁场, 低过热度, 微观组织, 非枝晶

Abstract: With the casting temperature lowered properly and an electromagnetic field applied to the preparation of ZL201 alloy, the solidified structure and its refining mechanism were investigated. The results revealed that the alloy is of a homogeneous, fine and non-dentritic crystalline structure which tends to be finer and more homogeneous with the increasing current and enhanced cooling effect. When casting at near-liquidus temperature, the radius of critical crystal nucleus decreases and, meanwhile, the melt temperature gradient decreases under the action of electromagnetic field, thus stimulating the formation of quasi-solid radicals to increase nucleation rate and making the structure finer and more homogeneous. During the initial solidification the growth rates of crystal nuclei in diverse directions tend to the same with grains growing up in sphere-like shape, since the distribution of solutes becomes uniform under the action of electromagnetic field.