(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Cu-5%Cr（摩爾分?jǐn)?shù)）過共晶合金深過冷快速凝固組織的演變規(guī)律。研究表明，隨著過冷度增大，Cr的組織轉(zhuǎn)變有3個(gè)階段:首先初生相Cr由長(zhǎng)條狀轉(zhuǎn)變?yōu)榍驙睿珻r顆粒的直徑被細(xì)化至2μm；其次當(dāng)過冷度進(jìn)一步增大，初生相Cr的結(jié)晶被完全抑制，結(jié)晶進(jìn)入擴(kuò)展共晶區(qū)形成完全的共晶組織，Cr顆粒的直徑被細(xì)化至0.5μm；最后當(dāng)過冷度進(jìn)一步增大，Cu-5%Cr過共晶合金獲得絕對(duì)穩(wěn)定平界面生長(zhǎng)，生成超飽和的單相Cu-Cr固溶體合金。隨著Cr顆粒的細(xì)化，Cr中固溶Cu組元含量不斷增大，實(shí)際上形成了富Cr和富Cu的兩個(gè)區(qū)域。
關(guān)鍵字: Cu-Cr合金； 落管； 深過冷； 共晶組織； 絕對(duì)穩(wěn)定平界面生長(zhǎng)
（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
