冷却速率对急冷Fe-Al-Nb三元合金凝固组织形成的影响  

Influence of Cooling Rate on Microstructural Formation of Melt-Spun Fe-Al-Nb Ternary Alloy

作　　者：谷倩倩 阮莹[1] 朱海哲 闫娜[1] 

机构地区：[1]西北工业大学应用物理系,西安710072

出　　处：《金属学报》2017年第6期641-647,共7页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.51327901;U1660108;51301138;航空科学基金项目No.2014ZF53069;陕西省科学技术研究发展计划工业科技攻关项目No.2016GY-247;西北工业大学基础研究基金项目No.3102015ZY077~~

摘　　要：采用单辊急冷技术研究了Fe_(67.5)Al_(22.8)Nb_(9.7)三元合金的快速凝固和组织形成规律。当辊速从10 m/s增大到40 m/s时,合金条带厚度减少1个数量级,冷速增加了7倍;辊速为40 m/s时样品形状除规则条带外还出现了鱼骨状条带和球状液滴。合金显微组织由Nb(Fe,Al)_2和a-Fe组成,随着辊速增大,凝固组织特征发生变化并且显著细化。随着辊速的增大,合金条带近自由面凝固组织则由初生a-Fe相和层片共晶向碎断层片共晶转变,近辊面凝固组织始终由不规则共晶组成。辊速达到40 m/s时,规则条带完全由不规则共晶组成;合金液滴由于获得的冷速相对较低,其凝固组织主要由初生a-Fe相和层片共晶组成,且随着液滴直径的减小初生相由树枝晶向等轴晶转变。Fe-Al-Nb ternary alloys as a sort of high-temperature structure materials are paid more attention in recent years. The pseudobinary eutectic composed of Nb（Fe, Al）2 and α-Fe phases in Fe-Al-Nb alloy transformed from lamellar shape to fiber with the increase of growth rate in directional solidification. Heat treatment techniques were applied to investigate the strengthening mechanism related to microstructural formation. However, influence of cooling rate on microstructure especially pseudobinary eutectic is not clear yet. In this work, rapid solidification and the microstructural formation of Fe67.5Al22.8Nb9.7 ternary alloy were investigated by melt spinning technique to reveal the rapid solidification mechanism of the alloy. As the wheel rate increases from 10 m/s to 40 m/s, the thickness of alloy ribbon decrease by one order of magnitude, i.e. from 67.70 μm to 4.69 μm, the cooling rate increases by seven times, i.e. from 1.24×10^6 K/s to 9.53×10^6 K/s. Consequently, the sample shape transforms from regular ribbon to regular ribbon, fishbone-like ribbon and droplets. The microstructure consists of Nb（Fe, Al）2 and α-Fe phases. The rise of wheel rate leaded to the microstructural transition and refinement, as well as the refinement in terms of eutectic interlamellar spacing and grain size （i.e. grain diameter） measured using Image-Pro Plus software. On condition that the wheel rate is less than 40 m/s, the ribbon microstructural characteristics are divided into two regions, i.e. primary α-Fe phase plus lamellar pseudobinary eutectic near free surface region and anomalous pseudobinary eutectic near roller surface region. As the wheel rate increases from 10 m/s to 30 m/s, lamellar eutectic becomes fragmented and the amount of anomalous pseudobinary eutectic enlarges. Once the wheel rate is up to 40 m/s, anomalous pseudobinary eutectic is the only microstructure of the fishbone-like ribbon. Meanwhile, the alloy droplets with the diameter size ranging from 90 μm to 1500 μm were achieved at the whe

关 键 词：Fe-Al-Nb三元合金 快速凝固 显微组织 冷却速率 共晶 

分 类 号：TG113[金属学及工艺—物理冶金]