定向凝固条件下Al-35%La过共晶合金的组织演变  

Microstructural Evolution of Al-35%La Hypereutectic Alloy under Directional Solidification

作　　者：郑亚虹[1,2] 王自东[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]无锡市广播电视大学,江苏无锡214011

出　　处：《材料科学与工程学报》2010年第1期8-12,30,共6页Journal of Materials Science and Engineering

基　　金：国家重大基础研究发展计划资助项目(2006CB605200)

摘　　要：在常规凝固条件下,Al-35%La过共晶合金可形成周期性双相枝晶组织,这种组织类似于带状组织,即其中枝晶的成分沿生长方向是周期性变化的。为了研究这种组织的形成条件,采用定向凝固技术研究了凝固速度对Al-35%La合金形貌特征的影响。结果表明:在不同凝固速度条件下,Al-35%La合金均形成周期性双相枝晶组织;同时发现:随着凝固速度的提高,初生相Al11La3呈现从周期性双相胞晶→周期性双相枝晶→周期性双相细胞晶的演变规律。在此基础上,讨论了这些组织形态的形成机理。Under conventional solidification,microstructure of Al-35%La hypereutectic alloy formed a periodic two-phase dendritic structure,similar to band structure,the composition of the periodic two-phase dendrites exhibits periodical behavior along their growth direction.To study the conditions for forming this kind of structure,directional solidification technique was adopted to study the morphological transformation of Al-35%La alloy under different solidification rates.The results show that the structure of Al-35%La alloy retains the feature of periodic two-phase dendrites under different solidification rates.At the same time,with increasing solidification rate,the morphology of primary Al_（11）La_3 changes from periodic two-phase cell growth to periodic two-phase dendrites,and then to periodic two-phase thin cell growth.Additionally,the mechanism of forming a variety of morphologies was discussed.

关 键 词：Al-35%La合金 定向凝固 周期性双相枝晶 组织演变 

分 类 号：TG146.21[一般工业技术—材料科学与工程]