(1. 福州大學(xué) 材料科學(xué)與工程學(xué)院, 福州350002;
2. 西北工業(yè)大學(xué) 應(yīng)用物理系, 西安710072)
摘 要: 采用3m落管實(shí)驗(yàn)裝置研究了Fe-Sn偏晶合金深過冷快速凝固組織。 結(jié)果顯示在大的過冷度下, 亞偏晶合金, 偏晶合金和過偏晶Fe-Sn合金均獲得了組織均勻的兩相共生組織, 表明在過冷條件下偏晶相圖具有與共晶相圖相似的偏晶共生區(qū)。在過偏晶合金中, 富Sn液相優(yōu)先聚集生長, 具有調(diào)幅分解生長特征; 而在亞偏晶合金中, 領(lǐng)先形成相為Fe的固溶體, 它以形核長大的方式進(jìn)行。 在Fe-26.2%Sn亞偏晶合金中, 首次獲得了絕對穩(wěn)定平界面生長單相組織, 實(shí)際的溶質(zhì)分配系數(shù)kV→1, 經(jīng)計(jì)算, 獲得絕對穩(wěn)定平界面生長的臨界過冷度為588K, ΔT=0.4TL, 對應(yīng)的生長速度為38.3m/s。
關(guān)鍵字: 偏晶合金; 深過冷; 落管; 共生組織; 平界面生長
（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
