电解铝液中的Fe、Si、H、氧化铝夹杂对Al-Zn-Mg-Cu合金组织性能的影响  

Effects of Fe, Si, H and oxide inclusions in electrolyte liquid-Al on microstructure and mechanical properties of Al-Zn-Mg-Cu based alloys

作　　者：贺永东[1] 张新明[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《材料热处理学报》2006年第4期95-100,共6页Transactions of Materials and Heat Treatment

基　　金：国家重大基础研究发展规划项目(2005CB623706)

摘　　要：采用扫描电镜、透射电镜、能谱分析等手段研究了电解铝液中的铁、硅、氢、氧化夹杂对Al-Zn-Mg-Cu合金组织性能的遗传影响。结果表明:电解铝液中形成的氢和氧化夹杂是相互影响的,铝液中的氢主要寄生于氧化物夹杂上。氧化物夹杂不被铝液润湿,在合金凝固过程中,作为氢气泡形核基底的氧化物夹杂,易被枝晶组织推向晶界,在晶界上形成杂、气共生的夹渣、疏松、气孔,疏松和气孔是铸态、均匀化态Al-Zn-Mg-Cu合金断裂的原因。电解铝液中的铁、硅杂质与合金中的Mn、Cu等元素作用形成AlFeMnSi、Al6(FeMn)、Al7Cu2Fe等难溶相,分布于晶内、晶界。均匀化处理过程中,难溶相发生球化。合金经热轧变形后,难溶相发生破粹并沿轧线呈带状分。硬脆的难溶相作为潜在的裂纹源,是造成峰值时效态合金断裂的原因。The effects of Fe, Si, H and oxide inclusions in electrolyte liquid-Al on microstructures and properties of Al-Zn-Mg-Cu alloys were studied by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The results show that hydrogen and oxide inclusions in the electrolyte liquid-Al interacts each other. Hydrogen is mainly on oxide inclusions. Oxide inclusions are not wetted by liquid-Al and they act as sites of hydrogen cavity nucleation and easily be pushed up to the boundary by the dendrite during solidification. There are intergrowth of hydrogen cavity and oxide inclusions at grain boundary forming residue and gas porosity. The existence of gas porosity is responsible for fracture of the as-cast and homogenized Al-Zn-Mg-Cu alloys under loading. Impurity of Fe and Si in electrolyte liquid-Al reacts with Cu and Mn to form insoluble phases of AlFeMnSi, AL6 (FeMn) and Al7Cu2Fe. These phases distribute within grains and on grain boundaries and is sphericized during homogenization. The insoluble phases are broken during hot-rolling and distribute in the direction of rolling. The hard and brittle insoluble phases act as potential crack source leading to fracture of the aged alloys under loading.

关 键 词：AL-ZN-MG-CU合金 组织 氧化铝夹杂 冶金遗传 

分 类 号：TG166.3[金属学及工艺—热处理]