Fe_(40)Ni_(40)B_(20)共晶合金深过冷凝固组织演化的温度曲线及高速摄影分析  

Microstructure Evolution of Deeply Undercooled Fe_(40)Ni_(40)B_(20) Eutectic Alloys:Cooling Curves and HSV Images Analysis

作　　者：张柯 刘峰[2] Zhang Ke;Liu Feng(School of Mechanical Engineering,Shaanxi Key Laboratory of Advanced Manufacturing and Evaluation of Robot Key Components,Baoji University of Arts and Sciences,Baoji 721016,China;State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]宝鸡文理学院机械工程学院,陕西省机器人关键零部件先进制造与评估省市共建重点实验室,陕西宝鸡721016 [2]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《稀有金属材料与工程》2022年第5期1813-1820,共8页Rare Metal Materials and Engineering

基　　金：陕西省教育厅专项科研计划(19JK0037);陕西省重点研发计划(2021GY-326);国家自然科学基金(8207070740)。

摘　　要：采用红外测温仪结合高速摄影,对Fe_(40)Ni_(40)B_(20)(at%)共晶合金深过冷熔凝过程温度曲线及凝固过程影像进行监测和记录。基于获得的高速摄影图像及温度曲线结果,结合合金对应凝固条件下组织特征分析,发现深过冷条件下合金的凝固组织随过冷度(ΔT)存在3个典型演化过程:ΔT=170~230 K,规则棒状亚稳相共晶团组织初始形成,随后残余液相中稳定两相凝固及初始亚稳组织重熔,分别对应温度曲线及高速摄影图像中的一、二次再辉;ΔT=230~260 K,规则棒状及近非规则亚稳相共晶团组织形成、亚稳相分解及残余液相中稳定相外延生长,表现为温度曲线及高速摄影图像中仅有一次再辉过程;ΔT=260~300 K,非耦合生长非规则亚稳相共晶团组织的形成,亚稳相的后续分解,表现为温度曲线中出现拐折及高速摄影图像中存在二次再辉现象。高速摄影测得一次再辉对应凝固速率表明,大过冷范围随着ΔT增大,初生组织凝固速率出现先增大而后稳定的现象;采用枝晶生长模型近似计算的亚稳相生长速率在中大过冷范围与测得一次凝固速率较好吻合,更大过冷范围速率稳定归因于生长机制转变为两相的非耦合生长,也很好的印证了以上组织演化规律。The temperature curves and the images of solidification for Fe_(40)Ni_(40)B_(20)(at%)eutectic alloys were detected and recorded by using the infrared pyrometer and the high speed video(HSV).Combining with the previous DSC results,three evolution regions can be deduced for the microstructure with initial melts undercoolings(ΔT):ΔT=170~230 K,the rod eutectic colonies of metastable phase(Fe,Ni)_(23)B_(6) andγ-(Fe,Ni)forms initially which gives birth to the first recalescence in temperature curve and HSV Images.Subsequently,the stable phasesγ-(Fe,Ni)and(Fe,Ni)3B solidify from remaining melts and the metastable phases remelt which causes the second recalescence;ΔT=230~260 K,the rod eutectic colonies or near uncoupled two phases with metastable phase solidify from undercooled melts initially and transform into stable phases during further cooling,the stable phase form epitaxially from the matrix phase of the initial colonies almost simultaneously.Therefore only one sharp recalescence peak can be obtained from temperature curve which corresponding to one brightening process from HSV.ΔT=260~300 K,The uncoupled growth betweenγ-(Fe,Ni)and(Fe,Ni)_(23)B_(6) appears and forms the anomalous eutectic structure.The severe decomposition of metastable give rise to the inflexion on the temperature curve and the second recalescence in HSV images.The solidification rates of metastable phase were calculated by using BCT model which coincide with the rates first recalescence in the region of medium and largeΔT.With further increasingΔT,the recalescence rates deviate from the model results and keep almost steady values due to uncoupled growth of two phases.

关 键 词：共晶合金 深过冷 温度曲线 高速摄影 

分 类 号：TG113.12[金属学及工艺—物理冶金]