于洵,王琳琳,欧美琼,马颖澈,辛啟斌,刘奎.一种新型高温合金凝固组织和元素偏析行为研究[J].稀有金属材料与工程,2019,48(5):1488~1496.[yuxun,wanglinlin,欧美琼,mayingche,xinqibin,liukui.SOLIDIFICATION CHARACTERISTIC AND SEGREGATION BEHAVIOR OF A NEW NICKEL BASE K4750 ALLOY[J].Rare Metal Materials and Engineering,2019,48(5):1488~1496.]
一种新型高温合金凝固组织和元素偏析行为研究
投稿时间:2017-12-26  修订日期:2018-03-06
中文关键词:  元素偏析,Thermo-Calc热力学平衡模拟计算,铸造高温合金
基金项目:
中文摘要:
      采用热力学平衡模拟计算、差热分析(DTA)和等温凝固淬火试验(ISQ)相结合的方法对一种新型镍基高温合金K4750合金的凝固组织和主要元素的偏析行为进行研究。研究结果表明,实际K4750合金的固相线温度为1270℃,液相线温度为1350℃,MC型碳化物析出温度为1320℃;凝固顺序为l→γ(1350℃),l→γ+MC(1320℃)。K4750合金在凝固初期凝固速度较快,液相体积分数下降明显,凝固后期速度开始变慢,在1310℃-1290℃温度区间内枝晶间连通残余液相开始断开,同时会有大块状的MC相析出,进一步阻碍液相的连通,从而极易导致合金凝固疏松的形成。合金中W、Fe、Cr的溶质分配系数大于1,富集于枝晶干,为负偏析元素;Ti、Nb、C、Mo的溶质分配系数小于1,富集于枝晶间的液相中,为正偏析元素。
SOLIDIFICATION CHARACTERISTIC AND SEGREGATION BEHAVIOR OF A NEW NICKEL BASE K4750 ALLOY
英文关键词:Isothermal solidification quenching experiment  Thermal-Calc  Ni-based superalloy  Element segregation
英文摘要:
      At this stage, the aircraft engine material K4169 alloy is difficult to perform at high temperature. Therefore, a new nickel base K4750 is researched by IMR and Jiangsu ToLand Alloy Co. Ltd, which can serve at 750 oC. In order to get excellent properties, the solidification microstructures and elemental microsegregation behavior are researched to provide reliable data of the new alloy. The solidification microstructures and elemental microsegregation behavior of a new Ni-base superalloy K4750 was comparatively investigated by differential thermal analysis (DTA), Thermo-Calc calculation and isothermal solidification quenching (ISQ) experiment. The results of ISQ indicate that the temperature of liquidus and solidus of K4750 alloy was 1350 oC and 1270 oC respectively, and the precipitated temperature of MC carbide was 1320 oC. The temperature of liquidus obtained by DTA and Thermal-Calc was in close agreement with the the result of ISQ, but the temperature of solidus obtained by DTA and Thermal-Calc was 1306 oC and 1296 oC respectively. In the initial stage of the solidification process, the volume fraction of residual liquid decreased sharply. In solidification process within the temperature range of 1310 oC~1290 oC, the residual liquid in the interdendritic region transformed from connected channels to isolated micro-liquid pools. In the last stage of solidification, these isolated micro-liquid pools were quite sluggish and resulted in the formation of porosity. The microsegregation coefficients of W, Fe and Cr were larger than 1, so they were considered to be negative segregation elements and segregate in solid. In contrast, the microsegregation coefficients of Ti, Nb, C and Mo were less than 1, thus they were positive segregation elements and segregated in the liquid.
作者单位E-mail
于洵 中国科学院金属研究所 xy962466@163.com 
王琳琳 东北大学材料科学与工程学院 wangll@smm.neu.edu.cn 
欧美琼 中国科学院金属研究所 mqou@imr.ac.cn 
马颖澈 中国科学院金属研究所 ycma@imr.ac.cn 
辛啟斌 东北大学材料科学与工程学院  
刘奎 中国科学院金属研究所  
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