自由落体条件下Fe-23%Mo-27.5%Si三元包共晶合金的快速凝固.pdfVIP

学兔兔 Aug．2010 VOI．59 NO．8 自由落体条件下Fe一23％Mo一27．5％Si三元包共晶 合金的快速凝固 范 龙，鲁晓宇，代富平 (西北工业大学应用物理系，陕西西安710072) 摘要：采用落管无容器处理技术实现了Fe一23％Mo．27．5％Si-~元包共晶合金的快速凝固，获得直径为100～1 200 m的合 金粒子。研究发现，室温下凝固组织由包共晶组织和三相共晶组织[FeSi相+T。(Fe~Vlo Si )+MoSi2相】组成。随着粒子直径 的减小，初生FeSi~由粗大枝晶变为碎断枝晶，进一步变成不规则的粒状晶粒；共晶胞体积变小，其形貌由层片状变 为涡旋圈状。理论计算表明，随着液滴直径的减小，过冷度和冷却速率呈指数关系增大，试验中获得的最小粒径对应 的最大过冷厦达到420 K(0．2610。 关键词：三元包共晶；深过冷；快速凝固；相组成 中图分类号：TG13l 文献标识码：A 文章编号：1001—4977(2010)08—0775—05 Rapid Solidification of Fe-23％Mo一27．5％Si Quasiperitectic Alloy During Free Fall FAN Long，LU Xiao—yu，DAI Fu—ping (Department of Applied Physics，Northwestern Polytechnical University Xi’an 71 0072，Shaanxi，China) Abstract：Fe一23％MO一27．5％Si ternary quasiperitectic alloy was rapidly solidified bV 3 m—long drop tube．The diameter of the obtained droplets varies frOm 1 00 tO 1 200 pm．It was revealed that the microstructure of the alloy at room temperature iS composed of FeSi，T1 and MoSi2 intermetallic phases．The morphology of primary FeSI phase experienced a transition of“coarse dendrites broken dendrites-~anomalous grain”with the reducing of droplet diameter．It was also found that the volume of the eutectic cells reduced as the droplets became smaller，and their morphology transformed frOm Iayer to eddy structure．TheoreticaI analysis indicates that with the diminishing of the droplet diameter．undercooling and cooling rate increase rapidly In an exponentiaI manner．The obtained maximum undercooling of droplet iS 420 K(0．26 )． Key WOrds：ternary quasiperitectic alloy；deep undercooling；rapid solidification；phase composition 液态金属快速凝固机制、相变规律、组织形貌演 组织形态演变、相组成特点，有着重要的理论和工程 变是材料科学和凝聚态物理领域共同关注的研究热点。 意义。 包晶