(东北大学 材料电磁过程教育部重点实验室， 沈阳 110006)
摘 要: 研究了电磁振荡对7075铝合金半连续铸锭微观组织及溶质元素宏观和微观分布的作用规律。研究结果表明： 存在一个最佳电磁场频率范围10～30Hz， 在此范围内， 随着交变磁场感应线圈电流增大， 铸锭中近球形组织增多， 蔷薇形组织减少， 晶粒尺寸变得更加细小和均匀；同时， 溶质元素晶内含量显著增加， 宏观偏析现象在很大程度上得到了抑制和消除； 此外， 电磁振荡使得液穴内部结晶核心增加， 温度场和含量场更趋均匀， 初凝壳高度和液穴深度降低，溶质元素分配系数增大和结晶区间变小， 对枝晶生长的抑制作用加强， 从而促进了电磁振荡法半连续铸锭中非枝晶组织的形成和溶质元素的强制固溶， 并且抑制了宏观偏析。
关键字: 电磁振荡； 半连铸； 铝合金； 微观组织； 固溶； 宏观偏析
（Key Laboratory of National Education Ministry for Electromagnetic Processing of Materials, Northeastern University, Shenyang 110004, China）
Abstract:The microstructure as well as solute distribution both in microscopic and macroscopic view for 7075 alloy by semi-continuous casting under the electromagnetic vibration were investigated. The results show that there is an optimum frequency range of 10～30Hz, in which, with the increasing of electromagnetic intensity, the quantity of spheroid-shaped grains increases; the quantity of rosette-shaped grains decreases, the microstructure of the ingot becomes more fine and uniform. At the mean time, alloying elements’ solubility increases and the macro-segregation is diminished in a great degree. The electromagnetic vibration makes the grain nuclei in sump increase, temperature and solute distribution of sump become uniform, primary solidified shell and sump height decrease, solute equilibrium partition coefficient increase and solidification temperature interval decrease, the effect of restraining crystal particles growing into dendrite strengthen, which promote alloying elements’ solution inside crystal and suppress macro-segregation.
Key words: electromagnetic vibration; semi-continuous casting; aluminum alloy; microstructure; solute distribution; macro-segregation
