冷却速率对急冷Fe-Al-Nb三元合金凝固组织形成的影响

发布时间：2018-11-21 15:14

【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。
[Abstract]:The rapid solidification and microstructure formation of Fe_ (67.5) Al_ (22.8) Nb_ (9.7) ternary alloy were studied by single roll quenching technique. When the roll speed increases from 10 m / s to 40 m / s, the thickness of the alloy strip decreases by 1 order of magnitude, and the cooling rate increases 7 times. When the roll speed is 40 m / s, the shape of the sample is not only the regular strip, but also the fishbone strip and the spherical droplet. The microstructure of the alloy is composed of Nb (Fe,Al) _ 2 and a-Fe. With the increase of roll speed, the solidification microstructure changes and refines remarkably. With the increase of roll speed, the solidification structure of alloy strip near free surface changes from primary a-Fe phase and lamellar eutectic to broken fault eutectic, and the solidification microstructure of near roll surface is always composed of irregular eutectic. When the roll speed reaches 40 m / s, the regular band is composed of irregular eutectic completely. The solidification structure of alloy droplets is mainly composed of primary a-Fe phase and lamellar eutectic due to the relatively low cooling rate obtained, and the primary phase changes from dendrite to equiaxed crystal with the decrease of droplet diameter.
【作者单位】：西北工业大学应用物理系;
【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~~
【分类号】：TG111.4

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