Rapid solidification of undercooled Al-Cu-Si eutectic alloys  

作　　者：RUAN Yina WEI BinaBo 

机构地区：[1]Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, China

出　　处：《Chinese Science Bulletin》2009年第1期53-58,共6页

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos.50121101,50395105);the Doctorate Foundation of Northwestern Polytechnical University (Grant No.CX200419)

摘　　要：Under the conventional solidification condition,a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work,rapid solidification of an undercooled liquid Al80.4Cu13.6Si6 ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating. The re-lationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt. The maximum undercooling is 147 K (0.18TE). The undercooled ternary eutectic is composed of α(Al) solid solution,(Si) semiconductor and θ(CuAl2) intermetallic compound. In the (Al+Si+θ) ternary eutectic,(Si) faceted phase grows independently,while (Al) and θ non-faceted phases grow coopera-tively in the lamellar mode. When undercooling is small,only (Al) solid solution forms as the leading phase. Once undercooling exceeds 73 K,(Si) phase nucleates firstly and grows as the primary phase. The alloy microstructure consists of primary (Al) dendrite,(Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling,while at large undercooling primary (Si) block,(Al+θ) pseudo-binary eutectic and (Al+Si+θ) ternary eutectic coexist. As undercooling increases,the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases.Under the conventional solidification condition, a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work, rapid solidification of an undercooled liquid Al80.04Cu13.6Si8 ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating. The relationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt. The maximum undercooling is 147 K （0.18TE）. The undercooled ternary eutectic is composed of α（Al） solid solution, （Si） semiconductor and θ（CuAl2） intermetallic compound. In the （Al＋Si＋θ） ternary eutectic, （Si） faceted phase grows independently, while （Al） and θ non-faceted phases grow cooperatively in the lamellar mode. When undercooling is small, only （Al） solid solution forms as the leading phase. Once undercooling exceeds 73 K, （Si） phase nucleates firstly and grows as the primary phase. The alloy microstructure consists of primary （Al） dendrite, （Al＋θ） pseudobinary eutectic and （Al＋Si＋θ） ternary eutectic at small undercooling, while at large undercooling primary （Si） block, （Al＋θ） pseudobinary eutectic and （Al＋Si＋θ） ternary eutectic coexist. As undercooling increases, the volume fraction of primary （Al） dendrite decreases and that of primary （Si） block increases.

关 键 词：液体物理学 三重共晶 过冷现象 晶体成核 

分 类 号：O4[理学—物理]