RE对过共晶Al-80%Si合金凝固特性的影响  

EFFECTS OF RE ON THE SOLIDIFICAIION CHARACTERISTICS OF Al-80% Si ALLOY

作　　者：文强[1] 坚增运[1] 朱满[1] 常芳娥[1] 党博[1] 

机构地区：[1]西安工业大学陕西省光电功能材料与器件重点实验室,西安710021

出　　处：《金属学报》2014年第5期610-618,共9页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展计划项目2011CB610403;国家自然科学基金项目51371133;51071115和51171136资助~~

摘　　要：利用高速摄影仪和SEM研究了RE对Al-80%Si合金凝固过程中再辉界面形貌、初生Si形貌和凝固后组织的影响.结果发现,加入RE前后的Al-80%Si合金均存在2个临界过冷度DT1和DT2,在过冷度小于DT1时,初生Si的形貌为粗大的长片状,表面有明显的棱角;过冷度大于DT2后,合金在凝固过程中的再辉界面为平面状,凝固后的初生Si形貌为均匀、细小、表面有光滑凸起的球状,并且晶粒表面的棱角消失;当过冷度在DT1与DT2之间时,合金在凝固过程中的再辉界面为树枝状,凝固后的初生Si形貌部分为表面有棱角的片状和块状,部分为表面无棱角的球状.对于Al-80%Si合金而言,DT1和DT2分别约为132和250 K.RE能降低Al-80%Si合金DT1和DT2的值,对于Al-80%Si-1%RE而言,DT1和DT2分别约为60和199 K.Effects of rare earth （RE） on the morphologies of the recalescence interface, the growing primary Si during the solidification process and the structure after solidification of A1-80% Si alloy were investigated by means of high speed camera and SEM. The critical undercooling △T1 and △T2 for the morphology transition of the recalescence interface, the growing primary Si and the structure have been obtained. When the undercooling is lower than △T1, the morphology of the growing crystal during the solidification process is flake-like; and the struc- ture after the solidification process is composed of large flake grains with pronounced edges and faces. When the undercooling is greater than △T1, the recalescence interface is a parallel one, and the structure after solidification is composed of homogenous and fine grains, and there exist several smooth spherical bulges on the surface of each grain. In the undercooling region from △T1 to △T2, the recalescence interface and the growing crystal show den- dritic features, but some of the dendrites are distributed regularly; after solidification, the structure is composed of refined equiaxed grains and flake grains. ForA1-80%Si alloy, △T1 and △T2 are equal to 132 and 250 K, respective- ly. RE can reduce the values of △T1 and △T2. When 1%RE is added into the alloy, △T1 and △T2 are changed to 60 and 199 K, respectively.

关 键 词：AL-SI合金 初生SI RE 过冷度 组织 

分 类 号：TG111.4[金属学及工艺—物理冶金]