摘要
采用液态金属冷却定向凝固工艺制备NbC纤维增强高温共晶镍基合金。利用SEM、XRD、EDS和EPMA等测试方法,对NbC纤维增强高温共晶镍基合金不同区域的显微组织及形成机理进行分析,随后分别改变抽拉速率(2、7、12μm/s)和熔体温度(1 550、1 580、1 600℃),研究工艺参数对合金组织的影响。根据组织类型及形态不同,可将定向凝固高温共晶镍基合金分为启动区与复合区两个区域,启动区以大块状的富Nb和富W碳化物为主,而位于启动区之上的复合区主要分布定向排列的NbC纤维。定向凝固过程中NbC纤维的生长可划分为3个阶段,即启动阶段、多取向竞争阶段和稳定阶段。随抽拉速率增大,纤维体积分数增大,纤维中C、Nb和W质量分数降低,且Nb含量下降更显著。随熔体温度升高,纤维体积分数、横截面积以及间距皆增大,纤维中C、Nb和W质量分数升高,且W含量上升更显著。
NbC fiber reinforced high-temperature eutectic nickel-based alloys were prepared using liquid metal cooling(LMC)directional solidification process.By using methods such as SEM,XRD,EDS,and EPMA,the microstructures and formation mechanisms of eutectic nickel-based alloys in different regions were analysed.The effects of various process parameters,including the pulling rates(v=2、7 and 12μm/s)and melt temperatures(T=1550、1580 and 1600℃),on the microstructures were studied.According to the differences in microstructural types and morphologies,directionally solidified eutectic nickel-based alloys can be divided into two regions,i.e.the start zone and the composite zone.The start zone is mainly composed of Nb-rich and W-rich block carbides,while the composite zone above the start zone is mainly composed of distributed NbC fibers arranged in a directional manner.The growth of NbC fibers during directional solidification can be divided into three stagess,namely,the initial stage,competitive stage,and stabilizing stage,based on the changes in morphology and special distribution of the NbC phase.As the pulling rate increases,the volume fraction of the NbC fiber increases,and the mass fractions of C,Nb,and W in the NbC fibers decreases,with a more significant decrease in the Nb content.As the melt temperature increases,the volume fraction,cross-sectional area,and spacing of the NbC fibers all increase,and the mass fractions of C,Nb,and W in the NbC fibers also increase,with a more significant increase in the W content.
作者
裴家纬
杨敏
杨东伟
崔婷婷
杨帆
郭敏
杨文超
张军
PEI Jiawei;YANG Min;YANG Dongwei;CUI Tingting;YANG Fan;GUO Min;YANG Wenchao;ZHANG Jun(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China)
出处
《铸造技术》
CAS
2024年第2期126-133,共8页
Foundry Technology
基金
国家自然科学基金(52031012,52301171)
凝固技术国家重点实验室自主研究课题(2022-TZ-01)
国家科技重大专项(J2019-Ⅵ-20-135)
陕西省科技创新团队计划(2021TD-17)。
关键词
共晶镍基合金
碳化物纤维
凝固组织
熔体温度
抽拉速率
eutectic nickel-based alloy
carbide fiber
solidified structure
melt temperature
pulling rate
