(1. 江西理工大学 机电工程学院，赣州 341000； 2. 江西理工大学 材料科学与工程学院，赣州 341000)
摘 要: 采用自行设计的电磁调控装置对结晶器内的铝熔体施加双向电磁搅拌处理，获得凝固组织为球状或类球状初生固相颗粒的半固态浆料，分析在电磁搅拌时间恒定12 s时磁场频率、电磁搅拌方式(单向连续电磁搅拌、双向连续电磁搅拌、双向间歇电磁搅拌)对初生相形貌演化的影响。结果表明：随着磁场频率的增加，初生固相晶粒的生长形态由树枝状、长条状、粗颗粒状转变为球状；晶粒尺寸先减小后增大；磁场频率存在最佳值30 Hz 。此时，初生相α(Al)的平均等积圆直径为38.2 μm，形状因子为0.75。此外，双向连续电磁搅拌作用于液态熔体形成强烈的紊流和惯性冲击，加快凝固体系的质量传输热量传递，合金浆料组织相较于单向连续电磁搅拌、双向间歇电磁搅拌更加细小圆整。
关键字: 半固态；A356铝合金；双向电磁搅拌；凝固组织
（1. School of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China; 2. School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China）
Abstract:A semi-solid slurry with solidified structure of spherical or spheroid primary solid particles was obtained by using a self-designed electromagnetic control device to two-way electromagnetic stirring the aluminum melt in the mold. The influences of magnetic field frequency and electromagnetic stirring ways (single way continuous electromagnetic stirring, two-way continuous electromagnetic stirring, two-way intermittent electromagnetic stirring) on the morphological evolution of the primary phase were analyzed when the electromagnetic stirring time was constant at 12s. The results show that, with the increase of the magnetic field frequency, the morphologies of primary solid phase grains change from dendritic, long strip, coarse granular to spherical shape, the grain size first decreases and then increases, the optimum magnetic field frequency is 30 Hz. In this case, the average equal-area circle diameter of primary α(Al) is 38.2 μm, and the average shape factor is 0.75. In addition, when two-way continuous electromagnetic stirring are applied on the liquid melt to form strong turbulence and inertial impact, the mass transfer and heat transfer of the solidified system are accelerated. The slurry structure of alloy is more compact and rounded than those by the single-way continuous electromagnetic stirring and two-way intermittent electromagnetic stirring.
Key words: semisolid; A356 aluminum; two-way electromagnetic stirring; solidification microstructure
