旋转磁场对凝固组织形成的影响  

Influence of rotating magnetic field on the formation of solidification microstructure

作　　者：陈钊[1] 陈长乐[1] 温晓莉[1] 文军[1] 

机构地区：[1]西北工业大学理学院,陕西省凝聚态结构与性质重点实验室,西安710072

出　　处：《物理学报》2008年第10期6277-6282,共6页Acta Physica Sinica

基　　金：国家自然科学基金重点项目(批准号:50331040);国家自然科学基金(批准号:60171034)资助的课题~~

摘　　要：研究了旋转磁场作用下Pb-45%Sn亚共晶合金的凝固组织.实验发现,旋转磁场的频率恒定时,凝固组织的晶粒尺寸随着磁场强度的增强而线性减小,同时,初生相的生长形态从枝晶转变为椭球状.X射线测试结果表明,初生相Pb发生了点阵膨胀,并且晶格常数随着磁场强度的增强先变大后减小,磁场强度在此存在一个临界值.能谱分析显示,随着磁场强度的增强,初生相Pb内Sn的含量逐渐降低.根据电磁场理论和扩散定律,对上述现象进行了理论分析,揭示出旋转磁场引起了液相强烈流动,加快了溶质原子的扩散以及对熔体的加热效应,导致了形核率的提高和长大速度的降低.The solidification microstructures of Pb-45% Sn hypoeutectic alloy in rotating magnetic field （RMF） were investigated. When the rotating frequency keeps constant, the grain size reduces linearly with the increase of magnetic intensity, and structure of the primary phase changes from the dendrite to spherical crystals. X-ray diffraction （XRD） measurement indicates that the RMF causes the lattice expansion of primary phase （Pb）, and the lattice parameter increases at first and then decreases with the increase of RMF intensity. Therefore,there is a critical value of magnetic intensity. Moreover,the Sn content in primary phase （Pb） reduces gradually with the increase of magnetic intensity. The results are analyzed theoretically based on electromagnetism field theory and scattering law. It is revealed that RMF causes severe fluid flow, and accelerates the diffusion of solute atom and heats the melt, which resuhs in the increase of nucleation rate and the decrease of growth velocity of crystal.

关 键 词：旋转磁场 液相流动 晶格常数 溶质分配 

分 类 号：O441.6[理学—电磁学]