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Effect of solid solution elements on cracking susceptibility of Ni-based superalloys during additive manufacturing

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Journal of Materials Science & Technology 2024年第23期190卷 218-228页

作者： Xue Zhang Yahang Mu Nannan Lu Qi Li Shaofeng Chen Yizhou Zhou xiaofeng sun Jingjing Liang Jinguo Li School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

Alloy composition design usually contributes to eliminating cracking in Ni-based superalloys during addi-tive manufacturing(AM).However,a detailed understanding of each solid solution element in the crack-ing susceptibility of Ni-based superalloys during AM is still *** newly designed alloys are considered to investigate the combined effect of solid solution elements on cracking *** behaviors of solidification cracking,liquation cracking,and solid-state cracking were analyzed by the microstructural characterization and thermodynamic *** results showed that W and Mo cause the formation of high melting-point carbides at grain boundaries(GBs),which increase solidifica-tion cracking ***,W and Mo lead to a slightly higher solidification cracking index(SCI)compared to Co,Cr,and *** the successive solidification and remelting process,the borides en-riched in W,Mo,and B around GBs will cause grain boundary segregation and liquation cracking.W and Re extend the freezing range(FR)and exacerbate the segregation of Al and Ti in the inter-dendritic re-gions,contributing to the formation of ***,complete or partial melting of the eutectic can induce liquation cracking during the thermal cycling in *** solid-state cracking susceptibility can be reduced by solid solution elements,especially Re and *** summary,compared to Co,Cr,and Re,W and Mo exacerbate the cracking susceptibility.

关键词： Additive manufacturing Ni-based superalloys Cracking susceptibility Solid solution elements

Crack growth behavior of SRR99 single crystal superalloy under thermal fatigue

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Rare Metals 2008年第5期27卷 526-530页

作者： LIU Yuan YU Jinjiang XU Yan sun xiaofeng GUAN Hengrong HU Zhuangqi Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Graduate School of Chinese Academy of Sciences Beijing 100039 China

The thermal fatigue behavior of a single crystal superalloy SRR99 was investigated. Specimens with V-type notch were tested at the peak temperatures of 900, 1000, and 1100℃. The crack growth curves as a function of the number of cycles were plotted. With the increase of peak temperature, the crack initiation life was shortened dramatically. Through optical microscopy （OM） and scanning electron microscopy （SEM） observation, it was found that multiple small cracks nucleated at the notch tip region but only one or two of them continued to develop in the following thermal cycles. The primary cracks generally propagated along a preferential direction. Microstructure changes after thermal fatigue were also discussed on the basis of SEM observation.

关键词： single crystal superalloy thermal fatigue crack growth behavior dendrite orientation

Influence of Substituting W for Nb or Hf on Solidification Behavior of a Typical Co-Ni-Al-W Based Superalloy

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Acta Metallurgica Sinica(English Letters) 2024年第11期37卷 1907-1920页

作者： Huifang Zhang Jun Xie Qi Li Hao Wu Jinjiang Yu Hongyu Chai Fengjiang Zhang Jinguo Li Yizhou Zhou xiaofeng sun Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026China

Understanding the effects of various elements on solidification behavior is crucial for designing the composition ofγ’-strengthened Co-based superalloys and is fundamental for controlling the as-cast structure and formulating subsequent heat treatment *** research investigated the effects of replacing 1 at.%W with 1 at.%Nb or Hf elements on the solidification behavior of Co-Ni-Al-W-based *** findings revealed that substituting W with Nb and Hf resulted in a notable decrease in both the solidus temperature(TS)and liquidus temperature(TL).Specifically,the substitution of W with Nb lowered TS from 1353℃ to 1332℃ and TL from 1383℃ to 1368℃,while replacing W with Hf decreased TS from 1353℃ to 1330℃ and TL from 1383℃ to 1366℃.Moreover,both Nb and Hf element are positive segregation element,while Nb decreases and Hf increases W segregation,*** the final solidification stage,the substitution of W with Nb resulted in the formation of eutectic(γ+γ’),Co_(3)Ta,and a small amount ofμ-Co7Nb6 phase,while replacing W with Hf resulted in the formation of the Laves phase andβ-CoAl *** solidification paths of the three alloys were confirmed based on the result of differential scanning calorimetry,isothermal solidification experiment and Thermo-calc *** results offer a theoretical basis for the composition design and optimization of heat treatment processes for Co-Ni-Al-W-based superalloys.

关键词： Co-Ni-Al-W-based superalloys Solidification microstructure Segregation Solidification path

EFFECT OF METAL-OXIDE DIFFUSION BARRIER ON INTERDIFFUSION OF ELEMENTS BETWEEN COATING AND SUBSTRATE

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Acta Metallurgica Sinica(English Letters) 1991年第9期4卷 174-178页

作者： sun Biwu GUAN Hengrong sun xiaofeng (Institute of Metal Research,Academia Sinica,Shenyang)LI Tiefan (Institute of Corrosion and Protection of Metals,Academia Sinica,Shenyang) Acad Sinica Shenyang China

The effect of LPPS Ni_3Al-Y_2O_3 diffusion barrier layer on interdiffusion of elements between coating and substrate has been *** was found that the retardation of interdiffusion is related to the amount of oxide in the diffusion barrier *** retardation is not remark- able when the content of Y_2O_3 is 8 wt-%,whereas the diffusion of Al,Co or Cr has all been notably retarded when the content of Y_2O_3 reaches 30 wt-%.The retardation effect of diffu- sion barrier is different for different elements such as Al,Co or Cr.

关键词： coating diffusion barrier diffusion

Effect of Phosphorus on Microstructure and High Temperature Properties of a Cast Ni-base Superalloy

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Journal of Materials Science & Technology 2002年第6期18卷 555-557页

作者： Chao YUAN, Fengshi YIN, xiaofeng sun, Hengrong GUAN and Zhuangqi HUInstitute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

Effect of phosphorus on the microstructure and high temperature properties of a cast Ni-base superalloy M963 has been investigated. SEM observation and EDS analysis showed that P was mostly enriched in the interdendritic region, and the P-rich phase was formed in the front position of finally solidified eutectics in high P doped alloys. It was found that the P-rich phase, as preferred initiation and propagation site of cracks, could aggravate the fracture process at high temperature in high P doped alloys. Consequently, high P addition would reduce remarkably the ductility and creep life of M963 superalloy at high temperature.

关键词： Phosphorus Cast superalloy Microstructure Mechanical properties

Effect of Ta on Tensile Behavior and Deformation Mechanism of a Nickel-Based Single Crystal Superalloy

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Acta Metallurgica Sinica(English Letters) 2024年第11期37卷 1921-1934页

作者： Mingtao Ge Xinguang Wang Yongmei Li Zihao Tan Xipeng Tao Yanhong Yang Liang Wang Chunhua Zhang Song Zhang Yizhou Zhou xiaofeng sun Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Shenyang University of TechnologyShenyang110870China

The effects of Ta on the tensile behavior and deformation mechanisms of a Ni-based single crystal superalloy were investigated in this study from room temperature to elevated *** findings demonstrated that the higher content of Ta could improve the tensile properties of the alloy at different *** to the different deformation mechanisms at various temperatures,the influence of Ta on tensile deformation *** room temperature,the higher content of Ta enhanced the solid solution strengthening,which would enhance the tensile strength of 6.5Ta *** standard heat treatment of 6.5Ta alloy,precipitation of the secondaryγʹphase would hinder the movement of *** the temperature was elevated to 760℃,the higher content of Ta not only promoted the interaction of stacking faults to form Lomer-Cottrell(L-C)locks that impeded dislocation motion,but also reduced the occurrence of dislocation pile-up groups,thus enhancing the yield *** 1120℃,due to the narrowerγchannels and higher APB energy inγʹphase of the alloy with higher Ta addition,the processes of bypassing and shearing of dislocations were hindered,***,the denser and more regular dislocation networks were formed in 6.5Ta alloy;and thus,the tensile strength of 6.5Ta alloy was *** study systematically investigated the effect of Ta on the tensile behavior at three different temperatures,which provided an important theoretical basis for the design of nickel-based single crystal superalloys in the future.

关键词： Ta Single crystal superalloy Tensile behavior Stacking fault Deformation mechanism

Effect of Substrate Characteristics on Interdiffusion Coefficients of Ni and Al Atoms in β-NiAl Phase of Aluminide Coatings

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Journal of Materials Science & Technology 2004年第2期20卷 196-198页

作者： Hua WEI, xiaofeng sun, Qi ZHENG, Guichen HOU, Hengrong GUAN and Zhuangqi HUInstitute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

Interdiffusion coefficients at 950℃ and 1050℃ are calculated by Wagner analysis method as a function of composition of β-NiAI phase. The β-NiAI phase is formed by pack cementation on surface of superalloy. Results of the calculation show that interdiffusion coefficients in β-NiAI phase strongly depend on the compositions and vary over several orders of magnitude. Compared with the interdiffusion coefficients in the stoichiometric β-NiAI phase, the interdiffusion coefficients in β-NiAI phase formed on superalloy is obviously small, probably due to the composition, complicated microstructure and precipitates. However, it could be seen clearly that the shapes of the diffusivity curves are very similar to each other. The similarity of the diffusion curves and the difference between interdiffusion coefficients imply that the compositions, microstructures and precipitates of superalloy have a distinctly adverse effect on the interdiffusion of Ni and Al atoms during aluminization, but do not change the essential characteristics of β-NiAI phase.

关键词： Aluminide coating Pack cementation,β-NiAl phase Aluminization Interdiffusion coefficient

Numerical simulation of nonlinear propagation of sound waves in a finite horn

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Chinese Journal of Acoustics 2015年第2期34卷 138-152页

作者： HOU Wei PAN Haoran SONG Weihua JING Xiaodong sun xiaofeng Beijing University of Aeronautics & Astronautics China Aero Shuangxing Technology Co.Ltd.

Nonlinear acoustic propagation generated by a piston in a finite horn is numerically studied. A quasi-one-dimensional nonlinear model with varying cross-section uses high-order low-dispersion numerical schemes to solve the governing equation. Because of the nonlinear wave distortion and reflected sound waves at the mouth, broadband time-domain impedance boundary conditions are employed. The impedance approximation can be optimized to identify the complex-conjugate pole-residue pairs of the impedance functions, which can be calculated by fast and efficient recursive convolution. The numerical results agree very well with experi- mental data in the situations of weak nonlinear wave propagation in an exponential horn, it is shown that the model can describe the broadband characteristics caused by nonlinear distortion. Moreover, finite-amplitude acoustic propagation in types of horns is simulated, including hyperbolic, conical, exponential and sinusoidal horns. It is found that sound pressure levels at the horn mouth are strongly affected by the horn profiles, the driving velocity and frequency of the piston. The paper also discusses the influence of the horn geometry on nonlinear waveform distortion.

关键词： Numerical simulation of nonlinear propagation of sound waves in a finite horn

Modern Translation of Classical Gardens:Landscape Design Conception and Strategy of Gaobeidian Train New Town in Longhu

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Journal of Landscape Research 2020年第1期12卷 1-5,8页

作者： sun Hu DENG Congshuang sun xiaofeng Guangzhou SPI Design Co. LTD

This study introduced the design process and main contents of a project called Gaobeidian Train New Town in Longhu,which won the excellence award in the 55th international competition in 2018 hosted by International Federation of Landscape Architects (IFLA).In view of the separation of traditional cultural heritage and modern society and the disappearance of traditional culture,this study put forward the design concept and strategy of connecting traditional culture and modern landscape with Ziquan Palace as the design prototype by means of elastic landscape design,so as to continue the gene of traditional culture and arouse people’s awareness of respecting and protecting traditional culture.

关键词： Landscape design IFLA in 2018 Traditional culture Modern landscape Elastic landscape