摘要
研究了电磁振荡对 70 75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。
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 10～30 Hz, 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.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2003年第5期1184-1191,共8页
The Chinese Journal of Nonferrous Metals
基金
国家重大基础发展规划项目 (G19990 64 90 5 0 1)
关键词
7075合金
电磁振荡
半连铸
铝合金
微观组织
固溶
宏观偏析
electromagnetic vibration
semi-continuous casting
aluminum alloy
microstructure
solute distribution
macro-segregation
