单晶高温合金定向凝固雀斑形成倾向液相密度差判据  

Liquid Density Difference Predictor for Freckle Formation Tendency of Single Crystal Superalloy during Directional Solidification

作　　者：姜卫国 韩东宇 董琳[1,2] 李相伟 李凯文 李强[1,2] Jiang Weiguo;Han Dongyu;Dong Lin;Li Xiangwei;Li Kaiwen;Li Qiang(Faculty of Electromechanical and Information,Weifang University of Science and Technology,Shouguang 262700,China;Weifang Key Laboratory of High-Temperature Materials and Single Crystal Components Fabrication Technology for Advance Engine System,Shouguang 262700,China;Institute of Metal Research,Chinese Academy of Science,Shenyang 110016,China;Centre of Excellence for Advanced Materials,Dongguan 523808,China)

机构地区：[1]潍坊科技学院机电信息学部,山东寿光262700 [2]潍坊市先进动力系统用热端材料及单晶部件制备重点实验室,山东寿光262700 [3]中国科学院金属研究所,辽宁沈阳110016 [4]东莞材料基因高等理工研究院,广东东莞523808

出　　处：《稀有金属》2023年第8期1113-1121,共9页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51674235)资助。

摘　　要：提出并采用合金熔体与枝晶间液体在液相线温度的密度差值用于预测单晶雀斑形成倾向。采用高速凝固工艺(HRS)及籽晶法制备一次枝晶取向为[001]的单晶高温合金试棒,统计了不同合金的雀斑平均总长度及一次枝晶间距,测量了不同合金的凝固温度区间及枝晶间区域成分,利用JMatPro软件计算母合金成分与枝晶间区域成分随温度变化的密度值。结果表明:不同成分单晶高温合金一次枝晶间距及合金凝固区间差别较大,一次枝晶间距与凝固温度范围与雀斑形成倾向不呈现线性关系;合金熔体(成分与母合金成分相同)与枝晶间液体(成分与枝晶间区域成分相同)在液相线温度的密度差与雀斑形成倾向呈较好的线性关系,采用该液相密度差值可以预判雀斑形成倾向大小。Single crystal Ni-based superalloys have been widely used to manufacture the turbine blade for both power generation and aeroengine.In order to increase the high temperature creep properties of single crystal superalloys,new single crystal superalloys with high content of W and Re are developed.The freckle defect,however,is easy to form in the single crystal superalloy components during directional solidification due to these refractory elements.Because of the harmful effect of freckle defect to the elevated temperature creep properties of single crystal superalloys,it is important to build a prediction criteria to assess the freckle formation tendency of single crystal castings.The density difference between the interdendritic liquid and bulk liquid at the liquidus temperature was employed to predict the freckle formation tendency,and the accuracy of this criteria was estimated by comparing with other criteria in this paper.The single crystal superalloy with different content of Re and W(%,mass fraction)was employed,and the content of refractory elements in Specimens 1~6 single crystal superalloy was 0Re+3.8W,0Re+7.5W,2.0Re+12.0W,2.0Re+11.0W,4.0Re+6.0W and 5.0Re+5.5W,respectively.The high-rate solidification process(HRS)and seed technology was conducted to prepare the single crystal superalloy bars with[001]orientation.The temperature of the furnace was 1500℃,and the directional solidification withdrawal rate was 3 mm·min-1.The freckle feature of different single crystal superalloy bars was observed by stereo microscope,and the average length of the freckles of each superalloy was counted by 12 bars.Optical microscope(OM)was employed to observe the microstructure,and the primary dendrite arm spacing was determined by count method.Differential scanning calorimetry(DSC)was used to test the solidification range of different single crystal superalloys.The composition of interdendritic region of single crystal superalloy bars was examined by electron probe microanalysis(EPMA).The density of the bulk liquid(composi

关 键 词：单晶高温合金 定向凝固 雀斑形成倾向 密度差 

分 类 号：TG27[金属学及工艺—铸造]