摘要
采用金相显微镜、扫描电镜和能谱分析等手段研究了在 Al Mg合金中同时添加等量的稀土元素 (La, Er) 和Zr后合金的铸态组织, 发现枝晶网胞尺寸明显减小, 晶粒细化, 同时有细小的Al3Zr粒子分布于晶内, 而Al RE化合物集中分布于晶界处. 存在两种细化机制, 生成的 Al3Zr质点在凝固过程中起非均质形核的作用, 稀土加入引起凝固过程中溶质再分配造成固液界面前沿成分过冷度增大.
Microstructures of casting Al-Mg alloy with equivalent amounts of Zirconium and Rare Earth elements (La,Er) were studied by means of optical microscopy,scanning electron microscopy and energy spectrum analysis.The results show that the addition of Zirconium and Rare Earth elements will remarkably decrease branching of the dendrites,thus refining the as-casting microstructure of Al-Mg alloy.Tiny particles of Al_3Zr with the crystal and lattice similar to Al matrix form and serve as sites for heterogeneous nucleation,while RE elements cause rapip build-up of a solute enriched zone due to its small solid solubility and then increase the undercooling on the solidification front.
出处
《材料与冶金学报》
CAS
2005年第1期55-59,共5页
Journal of Materials and Metallurgy
基金
军工配套项目"铝合金超塑性胀管坯料研究"资助.
关键词
铝合金
细化晶粒
异质形核
成分过冷
aluminium alloy
grain refinement
heterogeneous nucleation
undercooling
