(1. 福州大学 材料科学与工程学院, 福州350002;
2. 西北工业大学 应用物理系, 西安710072)
摘 要: 采用3m落管实验装置研究了Fe-Sn偏晶合金深过冷快速凝固组织。 结果显示在大的过冷度下, 亚偏晶合金, 偏晶合金和过偏晶Fe-Sn合金均获得了组织均匀的两相共生组织, 表明在过冷条件下偏晶相图具有与共晶相图相似的偏晶共生区。在过偏晶合金中, 富Sn液相优先聚集生长, 具有调幅分解生长特征; 而在亚偏晶合金中, 领先形成相为Fe的固溶体, 它以形核长大的方式进行。 在Fe-26.2%Sn亚偏晶合金中, 首次获得了绝对稳定平界面生长单相组织, 实际的溶质分配系数kV→1, 经计算, 获得绝对稳定平界面生长的临界过冷度为588K, ΔT=0.4TL, 对应的生长速度为38.3m/s。
关键字: 偏晶合金; 深过冷; 落管; 共生组织; 平界面生长
（1. School of Materials Science and Engineering,
Fuzhou University, Fuzhou 350002, China;
(2. Department of Applied Physics, Northwestern Polytechnical University ,
Xi′an 710072, China）
Abstract:The rapid solidification microstructures of Fe-Sn alloys at deep undercooling were studied by using 3m drop tube facility. The results show that the disperse microstructures of coupled growth of two phases are obtained in hypomonotectic, monotectic and hypermonotectic alloys under deep undercooling condition. It indicates that there is a monotectic coupled growth zone in monotectic phase diagram at deep undercooling condition, which is similar to that in eutectic phase diagram. Sn-rich liquid phase forms and grows firstly in hypermonotectic alloy, which grows in way of spinodal. The Fe solution forms firstly in hypomonotectic alloys, which grows in way of nucleation and growth. The absolute stable monophase microstructure with planar interface was obtained at first time in Fe-26.2%Sn hypomonotectic alloy with the real distributive coefficient of solute, kV, is close to 1. It is calculated that the critical undercooling of the alloy in growth way of absolute stable planar interface is 588K and its growth velocity is 38m/s. The critical undercooling is 0.4 times of the melt temperature of the alloy.
Key words: monotectic alloy; deep undercooling; drop tube; coupled growth structure; planar interface growth
