混沌对流下的半固态A356铝合金初生相形貌演变研究*
收稿日期: 2015-04-20
网络出版日期: 2015-10-16
基金资助
*国家自然科学基金项目51144009和51361012, 江西省自然科学基金项目20142bab206012以及江西省教育厅科技项目GJJ14407资助
RESEARCH ON MORPHOLOGY EVOLUTION OF PRIMARY PHASE IN SEMISOLID A356 ALLOY UNDER CHAOTIC ADVECTION
Received date: 2015-04-20
Online published: 2015-10-16
Supported by
Supported by National Natural Science Foundation of China (Nos.51144009 and 51361012), Natural Science Foundation of Jiangxi Province (No.20142bab206012) and Science and Technology Program of the Education Department of Jiangxi Province (NoGJJ14407)
研究了半固态A356铝合金熔体中混沌对流的表征, 及电磁场诱发的混沌对流对半固态A356铝合金熔体中初生相形貌演变的影响. 通过Fluent软件研究了电磁场作用下A356铝合金熔液中微粒的流动轨迹, 计算了这些流动轨迹的Kolmogorov熵和分形维数, 证明了施加适当的电流频率能在合金熔体中产生混沌运动. 结合实验研究, 对不同电流频率及工艺参数的实验结果进行对比. 研究结果表明, A356铝合金熔体在650 ℃浇注, 电流频率为30 Hz的电磁场中搅拌15 s, 并在590 ℃保温10 min, 此时凝固系统的Kolmogorov熵为6829.5 nat/s, 分形维数为2.2439, 初生相的平均等积圆直径为59.86 μm, 平均形状因子为0.71, 此时晶粒最圆整细小, 组织形貌最佳.
关键词： 半固态A356铝合金; 混沌对流; Kolmogorov熵; 分形维数; 电磁搅拌
刘政 , 张嘉艺 , 罗浩林 , 邓可月 . 混沌对流下的半固态A356铝合金初生相形貌演变研究*[J]. 金属学报, 2016 , 52(2) : 177 -183 . DOI: 10.11900/0412.1961.2015.00228
Chaotic advection could be strengthened mix, mass transfer and heat transfer in the viscous fluid, the melt flow forming was affected by electromagnetic field in the metal solidification process, so were the macro and microstructure of materials. So it was necessary to study chaotic characteristics of semisolid Al alloy in the electromagnetic field. The characterization of chaotic convention and morphology of primary phase were mainly researched in semisolid A356 alloy under the electromagnetic field. The trajectories of the particle in semisolid A356 alloy melt was simulated by the computational fluid dynamics software Fluent, the Kolmogorov entropy and fractal dimension of the flow trajectories of semisolid A356 alloy melt were judged and analyzed. The results showed that chaotic advection may happen in semisolid alloy melt under electromagnetic field. Combined with experiment, the results of process parameters and different current frequencies were compared. The results showed that the primary phase with 59.86 μm in average equal-area circle diameter, 0.71 in average shape factor, 6829.5 nat/s of Kolmogorov entropy and 2.2439 of fractal dimension can be obtained in semisolid A356 alloy with pouring 650 ℃, stirring for 15 s at 30 Hz, and holding at 590 ℃ for 10 min. Meanwhile, the morphology of primary phase can be observed with the best parameters.
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