混沌对流中不同稀土元素对半固态铝合金初生相形貌研究

发布时间：2018-04-04 05:53

本文选题：混沌对流　切入点：Kolmogorov熵　出处：《机械工程学报》2016年16期

【摘要】：研究不同半固态稀土铝合金熔体混沌对流的表征及在不同电磁搅拌频率和时间下诱发的混沌对流对加入相同量La及Yb的半固态A356铝合金初生相形貌演化的影响。用Fluent流体力学软件模拟电磁场作用下A356铝熔液中微粒的流动轨迹,计算流动轨迹的混沌特征量Kolmogorov熵,发现只要适当施加电磁场,Kolmogorov熵值随电磁搅拌频率及时间的增大而增加。结合试验,添加两种等量不同稀土对A356铝合金初生相形貌影响,并施加不同搅拌频率及时间的试验参数后,两者都在搅拌频率30 Hz、搅拌时间15 s时,初生相形貌最理想,晶粒细小圆整且Kolmogorov熵值达到最大。但A356-Yb铝合金的初生相形貌优于A356-La铝合金初生相形貌。通过模拟和试验,混沌看似无规则但其中暗含着规律,加入的稀土和施加的磁场频率及时间都互相影响混沌对流下的合金初生相形貌。
[Abstract]:The characterization of chaotic convection in different semisolid rare earth aluminum alloy melts and the effect of chaotic convection induced by different electromagnetic stirring frequency and time on the morphology evolution of semi-solid A356 aluminum alloy with the same amounts of La and Yb were studied.The Fluent fluid dynamics software is used to simulate the flow path of particles in A356 aluminum melt under the action of electromagnetic field. The chaotic characteristic quantity Kolmogorov entropy of the flow path is calculated. It is found that the value of Kolmogorov entropy increases with the increase of the frequency and time of electromagnetic stirring if the electromagnetic field is properly applied.Combined with the experiment, the morphology of primary phase of A356 aluminum alloy was affected by adding two kinds of different rare earth elements, and the primary phase morphology of A356 aluminum alloy was optimized when the stirring frequency and time were 30 Hz and 15 s, respectively.The grain size is fine and round and the Kolmogorov entropy is maximum.But the primary phase morphology of A356-Yb aluminum alloy is better than that of A356-La aluminum alloy.Through simulation and experiments, chaos appears to be irregular, but there is a law in it. The frequency and time of adding rare earth and applied magnetic field affect the morphology of the primary phase of the alloy under flow.
【作者单位】：江西理工大学机电工程学院;江西理工大学材料科学与工程学院;
【基金】：国家自然科学基金(51144009,51361012) 江西省自然科学基金(20114bab206014,20142bab206012) 江西省教育厅科技落地计划(KJLD12070);江西省教育厅科技(GJJ2014407)资助项目
【分类号】：TG292

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