Ni基单晶高温合金中γʹ粗化行为的电子显微学研究
周 慧，龙海波*，毛圣成, 张 泽，韩晓东
（1.北京工业大学材料与制造学部，北京100124；2. 浙江大学材料科学与工程学院，杭州浙江 310027）
摘 要 g′相是镍基单晶高温合金中主要强化相，研究g′相的热稳定性对于优化合金的高温服役性能具有重要指导作用。本文采用扫描电镜和透射电镜，研究了长期时效过程中镍基单晶高温合金中γ′相的粗化行为。研究发现在长期时效过程中g′相的尺寸逐渐增加，g′相的尺寸由初始的方块状演变为长条状。结合定量化分析，发现g′相尺寸的粗化速率逐渐降低、g′相体积分数先降后增。g′相尺寸在时效初始阶段遵循Ostwald熟化规律，粗化到一定程度会发生g′相合并，合并后便不再按Ostwald熟化规律增加。g′相尺寸体积分数变化规律是由外界温度升高及时间延长所引起的先回溶后脱溶所导致。
关键词 镍基单晶高温合金；g′相热稳定性；长期时效；显微结构
中图分类号：TG132.3+2；TG115.21+5.3；TB31
文献标识码：A doi:10.3969/j.issn.1000-6281.2022.04.003
Electron microscopic study on the coarsening behavior of γʹ in Ni-based single crystal superalloy
ZHOU Hui1，LONG Hai-bo1*，MAO Sheng-cheng1，ZHANG Ze2，HAN Xiao-dong1
(1. Faculty of Materials and Manufacturing，Beijing University of Technology，Beijing 100124；2. School of Materials Science and Engineering，Zhejiang University, Hangzhou Zhejiang 310008, China)
Abstract Theγ′ phase is the main strengthening phase in Ni-base single crystal superalloy. The study of the thermal stability of γ′ phase plays an essential ro1e in optimizing the service properties of alloy at high temperatures. This paper studied the coarsening behavior of γ′ phase in Ni-base single crystal superalloy during long-term aging by scanning electron and transmission electron microscopes. It is found that the size of γ′ phase increases with time, and the morphology of γ′ phase evolves from cubic to long strip shape during long-term aging. Combined with quantitative analysis, it is found that the coarsening rate of γ′ phase size decreases gradually, and the volume fraction of γ′ phase decreases at first and then increases. In the initial stage of aging, the size of γ′ phase follows the law of Ostwald aging. It will merge when coarsening to a certain extent, and it will no longer increase according to the law of Ostwald aging after the merge. The variation of the volume fraction of γ′ phase is caused by the increase of external temperature and the prolongation of time, which produces the first dissolution and then the re-dissolution process.
Keywords Ni-based single crystal superalloys；thermal stability of γ′ phase；long-term aging；microstructure
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