Competitive Nucleation and Rapid Growth of Co-Si Intermetallic Compounds during Eutectic Solidification under Containerless Processing Condition

查看全文 作　　者：Wenjing [1]Yao;Zipeng [1]Ye;Nan [1]Wang;Xiujun [2]Han;Jianyuan [1]Wang;Xixing [1]Wen 机构地区：[1]Department of Applied Physics, Northwestern Polyteehnical University, Xi'an 710072, China;[2]School of Materials Science, Shanghai Jiaotong University, Shanghai 200240, China 出　　处：《Journal of Materials Science & Technology》索引2011年第27卷第11期,共6页 基　　金：supported by the National Natural Science Foundations of China (Grant Nos. 50871090, 50971104 and 50901060);the NPU Foundations for Fundamental Research (JC20110279);the financial support from the National Aerospace Science Foundation of China (Grant Nos. 2008ZF53052 and 2010ZF53059) 摘　　要：The liquid-solid transitions of (Co2Si+CoSi) and (CoSi+CoSi2) eutectic alloys were realized in drop tube and the rapid eutectic growth mechanism of intermetallic compounds was examined. The experimental and calculated results indicate that with increasing Co content, the intermetallic compound prefers nucleating primarily. The eutectic microstructures experience the transitions of 'lamellar-anomalous-divorced' eutectic with undercooling. In undercooled state, the growth of CoSi intermetallic compound always lags behind others, and no matter how large the undercooling is, this intermetallic compound grows under the solutal diflusion control. The calculated coupled zone demonstrates that (Co2Si+CoSi) eutectic can form within certain undercooling regime, when the composition is in the range from 23.6% to 25.4% Si. And the calculated coupled zone of (CoSi+CoSi2) covers a composition range from 40.8% to 43.8% Si. 关 键 词：Liquid-solid transition Competitive nucleation Intermetallic compound UNDERCOOLING