(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Cu-5%Cr（摩尔分数）过共晶合金深过冷快速凝固组织的演变规律。研究表明，随着过冷度增大，Cr的组织转变有3个阶段:首先初生相Cr由长条状转变为球状，Cr颗粒的直径被细化至2μm；其次当过冷度进一步增大，初生相Cr的结晶被完全抑制，结晶进入扩展共晶区形成完全的共晶组织，Cr颗粒的直径被细化至0.5μm；最后当过冷度进一步增大，Cu-5%Cr过共晶合金获得绝对稳定平界面生长，生成超饱和的单相Cu-Cr固溶体合金。随着Cr颗粒的细化，Cr中固溶Cu组元含量不断增大，实际上形成了富Cr和富Cu的两个区域。
关键字: Cu-Cr合金； 落管； 深过冷； 共晶组织； 绝对稳定平界面生长
（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 Cu-5%Cr(in mole fraction) hypereutectic alloy at deep undercooling were studied by using three meters drop tube facility. The results show that there are three stages for the microstructures evolution of Cr with the increase of undercooling. Firstly, proeutectic Cr is formed from rod-like shape to spherical shape, with the diameter of Cr particle thinned down to 2μm; then the formation of proeutectic phase stops with the increase of undercooling, the crystallization is in the enlarged eutectic composition region of Cu-Cr phase diagram and the complete eutectic structure forms, with the diameter of Cr particle thinned down to 0.5μm; finally, the monophase supersaturation solid solution of Cu-5%Cr hypereutectic alloy develops in growth way of absolute stable planar interface with the further increase of undercooling. It is found that with the thinning of Cr particle, the content of Cu solved in Cr particle increases and the two regions of Cu-rich and Cr-rich form.
Key words: Cu-Cr alloy; drop tube; deep undercooling; eutectic structure; absolute stable planar interface growth
