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Effects of building orientation on fatigue behavior of Ti-6Al-4V alloy produced by selective laser melting

key Engineering materials 2019年 795卷 208-214页

作者： Xu, Rui Da Yu, Hui Chen AECC Key Laboratory of Aeronautical Materials Testing and Evaluation Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Beijing Institute of Aeronautical Materials Beijing100095 China

Addictive manufacturing (AM) allows for the layer-by-layer fabrication of components via sequential material deposition and it is of immediate interest in many applications, in particularly aviation field. This work is tackling the issue that the influence of the inner-defects and building orientations on the fatigue behavior of Ti-6Al-4V Alloys produced by Selective Laser Melting (SLM). Specimens were built in two orientations (horizontal and vertical to the substrate) in order to evaluate the impact of the induced anisotropy of fatigue properties. A series of fatigue tests at stress ratio R=-1 are conducted at 400°C. Scanning Electron Microscopy (SEM) is used to examine the fracture surfaces of fatigue specimens to qualify the failure mechanism and crack initiation sites, which are most likely attached to the surface defects. The fracture surface analysis of HCF specimen tested that most of the crack initiates from the defect under subsurface. The results of this study imply that the fatigue properties at 400℃ are highly dependent on the specimen orientations relative to build directions, as the defects close to surface are the mainly cause of the crack initiations. © 2019 Trans Tech Publications Ltd, Switzerland.

关键词： Scanning electron microscopy

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Research on Measurement technology of Residual Stress in Rolling Aluminium Alloys

Research on Measurement Technology of Residual Stress in Rol...

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第三届材料科学应用与能源材料国际研讨会

作者： Xi Wang AECC Beijing Institute of Aeronautical Materials Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Aviation Key Laboratory of Science and Technology on Materials Testing and Evaluation Key Laboratory of Aeronautical Materials Testing and Evaluation Aero Engine Corporation of China

In the measurement of textured materials such as Al Alloy sheet, the traditional method of X-ray residual measurement（sinψ method） cannot be applied to these materials. In this paper, 2 A97 aluminium lithium alloy was used for the study on residual stress measurement of texted materials. The X-ray diffraction method was used to test the orientation distribution function. The elastic constant of the material was calculated theoretically by Ruess model, Voigt model and Neerfeld-Hill model. And the residual stress was calculated. The blind-hole method was used to verify the results. The blind-hole result agreed well with the Neerfeld-Hill model.

关键词： Voigt Research on Measurement technology of Residual Stress in Rolling Aluminium Alloys

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Research Progress on Microstructure Characterization of Silicon Carbide Fibers

Research Progress on Microstructure Characterization of Sili...

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作者： Xingjian Zhang Zixi Cai Jinjuan Fan Changkui Liu Jinfa Ye AECC Beijing Institute of Aeronautical Materials Aviation Key Laboratory of Science and Technology on Materials Testing and Evaluation Northwestern Polytechnical University Queen Mary University of London Engineering SchoolNPU Fujian LEADASIA New Material Limited Company

Ceramic matrix composites have excellent properties such as high temperature resistance and oxidation resistance,and have good application prospects in the hot end parts of *** ceramic matrix composites,the microstructure composition of silicon carbide fibers determines their macroscopic ***,this article takes silicon carbide fiber as the research object,summarizes the existing SiC fibers structure,composition,and morphology characterization methods,compares the development and advantages and disadvantages of XRD,SEM,TEM and other testing equipment analysis,and proposes The problems of sample preparation,surface defects and internal structure changes in the microstructure characterization of silicon carbide fibers are discussed,which provides a reference for the preparation of high-performance SiC fibers and the improvement of their characterization work.

关键词： Silicon carbide fiber microstructure characterization method

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Influence of Inclusions' Position on Stress Distribution of Inclusion-matrix Interface 3

Influence of Inclusions' Position on Stress Distribution of ...

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3rd International Conference on Traffic Engineering and Transportation System, ICTETS 2019

作者： Zhao, Kai Wang, Tian-Yu Aecc Beijing Institute of Aeronautical Materials Beijing100095 China Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Beijing100095 China Key Laboratory of Science and Technology on Aeronautical Materials Testing and Evaluation Aero Engine Corporation of China Beijing100095 China Aviation Key Laboratory of Science and Technology on Materials Testing and Evaluation Beijing100095 China

In this paper, the influence of inclusions' position on stress & strain distribution was researched when inclusions were same size and shape. The finite element method was used to study the position effect of inclusions in the FGH95 P/M superalloys. The shape of inclusions was simplified rotundity in the model. The influence of inclusions which was on the surface, in the sub-surface and in the basic material on stress & strain distribution was studied. There were two cases, the inclusion connected basic material tightly and there was a hole between the inclusion and the basic material. The change rule of interfacial stress & strain distribution caused by the variation of inclusions' position was given. © Published under licence by IOP Publishing Ltd.

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Gaseous Scissor-mediated Electrochemical Exfoliation of Halogenated MXenes and its Boosting in Wear-Resisting Tribovoltaic Devices

arXiv

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arXiv 2024年

作者： Fan, Qi Chen, Minghua Li, Longyi Li, Minghui Xiao, Chuanxiao Zhao, Tianci Pan, Long Liang, Ningning Huang, Qing Zhu, Laipan Naguib, Michael Liang, Kun Zhejiang Key Laboratory of Data-Driven High-Safety Energy Materials and Applications Ningbo Key Laboratory of Special Energy Materials and Chemistry Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China University of Chinese Academy of Sciences 19 A Yuquan Rd Shijingshan District Beijing100049 China Beijing Key Laboratory of Micro-nano Energy and Sensor Center for High-Entropy Energy and Systems Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing101400 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China Ningbo New Materials Testing and Evaluation Center Co. Ltd Ningbo315201 China School of Physics and Optoelectronic Engineering Beijing University of Technology Beijing100124 China Key Laboratory of Advanced Metallic Materials of Jiangsu Province School of Materials Science and Engineering Southeast University Nanjing211189 China Qianwan Institute of CNITECH Ningbo315201 China Department of Physics and Engineering Physics Tulane University New OrleansLA70118 United States

Two-dimensional transition metal carbides (MXenes), especially their few-layered nanosheets, have triggered burgeoning research attentions owing to their superiorities including extraordinary conductivity, accessible active surface, and adjustable processability. Molten salts etching route further achieves their controllable surface chemistry. However, the method encounters challenges in achieving few-layer structures due to more complex delamination behaviors. Herein, we present an efficient strategy to fabricate Cl- or Br-terminated MXene nanoflakes with few-layers, achieved by electrochemical intercalation of Li ions and concomitant solvent molecules in the electrolyte solution, with gaseous scissors (propylene molecules) to break up interlayer forces. By controlling cut-off voltages, the optimal protocol results in nanosheets with an ultrahigh yield (~93%) and preserved surface chemistry. The resultant MXenes dispersions were employed as lubricants to enhance tribovoltaic nanogenerators, where Ti3C2Br2 displayed superior electrical output. These findings facilitate the understanding of MXenes’ intrinsic physical properties and enable the nanoengineering of advanced electronic devices. Copyright © 2024, The Authors. All rights reserved.

关键词： Nanosheets

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Three-dimensional neutron diffraction study of dendrite growth behavior in Ni-based single-crystal turbine blades

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Scripta Materialia 2025年 266卷

作者： Pucong Sheng Jiachen Long Nan Li Jingyi Zhou Yunsong Zhao Hao Lin Shengyi Zhong School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 PR China SJTU Paris Elite Institute of Technology Shanghai Jiao Tong University Shanghai 200240 PR China AECC Beijing Institute of Aeronautical Materials PR China Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation PR China Key Laboratory of Aeronautical Materials Testing and Evaluation Aero engine corporation of China PR China National Key Laboratory of Neutron Science and Technology PR China

Three-dimensional Neutron Diffraction (3DND) microscopy is performed using a monochromatic beam and applied for the first time to investigate the dendrite growth behavior in Ni-based single-crystal turbine blades. Leveraging the high penetration depth and non-destructive characterization capabilities of neutrons, 3DND provides a statistical analysis of crystallographic orientation distributions and stress states of single crystal at component level . In this study, lattice constants of both γ and γ' phases decrease progressively during dendritic growth, with γ phase exhibiting initial tensile strain that subsequently relaxed to zero. Misorientation analysis reveals a tilt misorientation reaching up to 5°, significantly larger than the twist of 1° Both types of misorientation increases as the dendrites develop, highlighting the anisotropic nature of microstructural evolution. These findings demonstrate the potential of 3DND for characterizing internal lattice strain, orientation distributions, and defect evolution in critical structural components, paving the way for improved manufacturing processes and material reliability.

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A Soothing Study: There is No Evidence of Microplastics in Meconium

SSRN

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SSRN 2022年

作者： Zhiming, Li Jiamin, Wang Jiaxin, Du Haixia, Sui Jieling, Wu Yizhou, Zhong Boxuan, Liang Hongyi, Xian Yuji, Huang Rongyi, Ye Xingfen, Yang Xia, Gao Zhenlie, Huang NMPA Key Laboratory for Safety Evaluation of Cosmetics Guangdong Provincial Key Laboratory of Tropical Disease Research Department of Toxicology School of Public Health Southern Medical University Guangzhou510515 China Beijing Key Laboratory of Organic Materials Testing Technology & Quality Evaluation Institute of Analysis and Testing Beijing Academy of Science and Technology Beijing Center for Physical and Chemical Analysis Beijing100089 China Division III of risk assessment China National Center for Food Safety Risk Assessment Beijing100022 China Department of Healthcare Guangdong Women and Children Hospital Guangzhou511442 China

Microplastics are a novel pollutant with widespread distribution in air, land and water. They have been detected in human stool, blood, lungs, and placentas. However, human fetal microplastic exposure remains largely under-studied. To assess fetal microplastic exposure, we investigated microplastics using 37 meconium samples. We developed a pretreatment method to separate microplastics from meconium, and analyzed 16 pretreated meconium samples with an ultra-depth three-dimensional microscope and Fourier transform infrared microspectroscopy. Our results showed that our pretreatment methods had good recovery and non-destructive advantages. We found no microplastics, but we did observe muscovite, octanoic hydrazide, and palmitic acid in the meconium samples. This indicates that microplastic pollution levels in the fetal living environment are miniscule, and thus we should shift our focus to fetal nanoplastics exposure. Moreover, our results underscore that comprehensive and strict quality control are necessary for further studies on microplastics exposure using human bio-samples. Additionally, we should not overlook the limitations of the human data presented in previous studies when we conduct risk assessment on human microplastics exposure. © 2022, The Authors. All rights reserved.

关键词： Risk assessment

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Study of the Residual Stress in 2A97 Al-Li Alloy Using Different Methods 2

Study of the Residual Stress in 2A97 Al-Li Alloy Using Diffe...

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2nd International Symposium on Application of materials science and Energy materials, SAMSE 2018

作者： Wang, Xi Liu, Changkui AECC Beijing Institute of Aeronautical Materials Beijing100095 China Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Beijing100095 China Aviation Key Laboratory of Science and Technology On Materials Testing and Evaluation Beijing100095 China Key Laboratory of Aeronautical Materials Testing and Evaluation Aero Engine Corporation of China Beijing100095 China

The contour method and X-ray diffraction have been used to measure the quenching stress in 2A97 Al-Li alloy. The surface stresses were measured by X-ray diffraction. Besides, the 2-D distribution of stresses have been given by the contour method. The differences between the two methods can be more than 100 MPa. In addition, finite element model which is suitable for evaluation of residual stresses in this material was established. There is very good correlation between the contour method and finite element model (FEM). The differences are less than 50MPa. The model has high precision to forecast the residual stress in 2A97 Al-Li alloy. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Residual stresses

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Influence of Quasi-Beta Heat Treatment on Acoustic Behaviors of Ultrasonic Inspection of TC4-DT Alloy

Influence of Quasi-Beta Heat Treatment on Acoustic Behaviors...

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Far East Forum on Nondestructive evaluation/testing: New technology & Application (FENDT)

作者： Xiang-Xi Gao Su-Jun Wu Chun-Hu Tao School of Materials Science and Engineering Beihang University (BUAA) Beijing PR China Aviation Key Laboratory of Science and Technology on Aeronautical Materials Testing and Evaluation Beijing PR China

ISBN: (数字)9781665440820

ISBN: (纸本)9781665440837

The microstructure and microtexture of TC4-DT alloy before and after quasi-β heat treatment are investigated, as well as the influence on the acoustic behaviors of ultrasonic inspection. C-scan ultrasonic images are obtained to investigate the evolution of microstructure confirmed by metallography and electron backscatter diffraction (EBSD) analysis. Noise level and signal-to-noise ratio (SNR) of ultrasonic inspection are also quantitatively verified. The results show that when TC4-DT alloy undergoes quasi-β heat treatment, attenuation and scattering of acoustic energy is significantly different. During this process, the scattering mechanism of acoustic changes from Rayleigh scattering to Phase scattering, which is mainly controlled by the grain size. Under the same scattering mechanism with the uniform average grain size, however, the regions of a-phase crystallites with a certain orientation contribute to the scattering of the acoustic wave. This finding is helpful for estimating ultrasonic inspection ability of large components.

关键词： Grain size Heat treatment Scattering Metals Inspection Microstructure Signal to noise ratio

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Effect of cold expansion on fatigue life of anodized Al alloy 2

Effect of cold expansion on fatigue life of anodized Al allo...

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2nd International Symposium on Application of materials science and Energy materials, SAMSE 2018

作者： Li, Nan Li, Haitao Liu, Hongtao Liu, Changkui AECC Beijing Institute of Aeronautical Materials Beijing100095 China Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Beijing100095 China Aviation Key Laboratory of Science and Technology On Materials Testing and Evaluation Beijing100095 China Key Laboratory of Aeronautical Materials Testing and Evaluation Aero Engine Corporation of China Beijing100095 China Structure Department Shenyang Aircraft Design Research Institute Shenyang110035 China

Anodizing treatment can improve corrosion resistance of aluminum alloy but decrease the fatigue life significantly. Introducing cold expansion before anodizing can increase the fatigue life of the specimen with open-hole structure by 2582% than the anodized one. Scanning electron microscopy (SEM) was employed for microstructure and fracture surface observation. Residual stress distribution near the sample hole edge was measured to elucidate the strengthening mechanism. The results revealed that although anodizing treatment decreases the surface integrity, the cold expansion is an effective method to improve the open-hole structure specimen remarkably. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Corrosion resistance

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