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梁静静,杨彦红,周亦胄,李金国,王亮,金涛,孙晓峰.激光立体成形镍基单晶高温合金显微组织研究[J].稀有金属材料与工程(英文),2017,46(12):3753~3759.[Liang Jingjing,Yang Yanhong,Zhou Yizhou,Li Jinguo,Wang Liang,Jin Tao,Sun Xiaofeng.Microstructures of Nickel-base Single-Crystal Superalloy Prepared by Laser Solid Forming[J].Rare Metal Materials and Engineering,2017,46(12):3753~3759.]
Microstructures of Nickel-base Single-Crystal Superalloy Prepared by Laser Solid Forming
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Received:October 21, 2016  Revised:December 16, 2016
DOI:
Key words: laser  solid forming, single  crystal superalloy, heat  treatment, recrystallization
Foundation item:国家自然科学基金资助(项目号51401210和U1508213)、国家高技术研究发展计划资助(2014AA041701)
Author NameAffiliationE-mail
Liang Jingjing Institute of Metal Research,Chinese Academy of Sciences jjliang@imr.ac.cn 
Yang Yanhong Institute of Metal Research,Chinese Academy of Sciences  
Zhou Yizhou Institute of Metal Research,Chinese Academy of Sciences  
Li Jinguo Institute of Metal Research,Chinese Academy of Sciences  
Wang Liang Institute of Metal Research,Chinese Academy of Sciences  
Jin Tao Institute of Metal Research,Chinese Academy of Sciences  
Sun Xiaofeng Institute of Metal Research,Chinese Academy of Sciences  
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Abstract:
      Single-crystal superalloys have been commonly used in modern advanced aero engines to produce high-pressure high-temperature turbine blades. In order to extend the lifetime of single-crystal turbine blades, repair of cracked and worn ones is of great interest. Laser Solid Forming (LSF) is a prospective technology that can be used to repair single-crystal blades. In this study, the microstructure of the as-deposited and heat-treated LSF single-crystal superalloy has been characterized through optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-deposited LSF sample showed a directionally solidified columnar dendrites growing almost parallel to the building direction. Between the dendrites, nearly round microporosity and blocky MC carbide particles were dispersed uniformly. TEM results indicated that many nano γ′ particles precipitated in γ matrix. In addition, during LSF deposition process, Stress was formed, which generated plenty of dislocations. During heat treatment, the LSF sample experienced fully recrystallization. The recrystallization grains were in different size, and twins were found in some recrystallized grains. Because the residual stress was fully released during heat treatment, the size and shape of γ′ precipitates in the recrystallized and un-recrystallized regions were similar to those in conventionally cast samples.