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Microstructural Degradation of Super304H after Long-Term Service Exposure

Defect and Diffusion Forum 2025年 439卷 209-219页

作者： Xu, Liming He, Yinsheng Shin, Keesam School of Mechanical and Energy Engineering Ningbo Tech University Ningbo315100 China National Center for Materials Service Safety University of Science and Technology Beijing Beijing100083 China School of Materials Science and Engineering Changwon National University Changwon51140 Korea Republic of

Super304H is austenitic steel used predominantly for boiler and turbine components in thermal power plants due to the high strength, excellent creep and oxidation resistance in hightemperature steam environments. Microstructural degradation is inevitable upon long-term hightemperature exposure. Therefore, understanding the processes of degradation is critical for the determination of residual lifetime of the parts. In this study, the hardness, tensile strength and creep strength of a Super304H steel that was in service as a reheater for ~8 years at about 600°C was investigated with corresponding microstructural analysis. Grain growth is evident, but microhardness and tensile strength did not decrease, due to the precipitation of nano-sized NbX and Cu-rich particles in grain interior. However, the creep rupture life of the aged S304H steel is ~90% lower at 650˚C than that of the virgin S304H, due to the coarsening of σ phase and formation of M23C6 on the grain boundary. Our measurements and analysis of the specimens in this study indicates the remaining service life longer than those in the NIMS database. © 2025 Trans Tech Publications Ltd, All Rights Reserved.

关键词： Grain growth

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Enhancing corrosion resistance of MAO coatings on Al alloy LY12 through in situ co-doping with zinc phosphate and cerium phosphate

Corrosion Communications

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Corrosion Communications 2025年第1期17卷 35-43页

作者： Chao Yang Tao Ying Aihui Huang Jian Huang Pinghu Chen Paul K.Chu Xiaoqin Zeng National Engineering Research Center of Light Alloy Net Forming School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai Key Laboratory of Advanced High-Temperature Materials and Precision Forming School of Materials Science and Engineering Shanghai Jiao Tong University Department of Chemistry University of Munich(LMU) College of Mechanical Engineering Key Laboratory of Hunan Province of Equipment Safety Service Technology under Extreme Environment University of South China Department of Physics Department of Materials Science&Engineering and Department of Biomedical Engineering City University of Hong Kong

Corrosion of aluminum（Al） alloys during service limits many applications. Micro-arc oxidation（MAO） coatings can enhance corrosion resistance, but porous defects in the films undermine their effectiveness. Here, by mixing a phosphate electrolyte with soluble Zn and Ce salts, zinc phosphate and cerium phosphate co-doped MAO corrosion-resistant coating is prepared on Al alloy LY12. Zinc phosphate and cerium phosphate are incorporated in situ to form an amorphous encapsulated nanocrystalline structure. During long-term corrosion, Zn2+is released and deposited as corrosion products Zn（OH）2to cover weak corrosion micro-regions in the coating. Simultaneously, Ce3+released from MAO coating co-doped with zinc phosphate/cerium phosphate forms Zn（OH）2/Ce（OH）3due to the small solubility product Kspto further enhance corrosion resistance. Compared to pristine Al alloy,corrosion potential increases from -1.306 to -0.819 VSCE, and corrosion current density decreases by 4 orders of magnitude from 2.6 × 10-6to 2.5 × 10-10A·cm-2. Co-doped MAO coating significantly enhances corrosion resistance of Al alloy LY12 and shows great potential for a wide range of applications.

关键词： Aluminum alloys Micro-arc oxidation coating Corrosion resistance Zinc phosphate Cerium phosphate

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Influences of Process Parameters and Addition Elements on the Fabrication of TiC-Ti3SiC2 Composites by Spark Sintering

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materials Transactions 2025年第5期66卷 608-615页

作者： Qu, Jing Matsugi, Kazuhiro Choi, Yongbum Xu, Zhefeng Yu, Jinku Department of Mechanical Materials Engineering Hiroshima University Higashihiroshima739-8527 Japan State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao066004 China

In TiC-Ti3SiC2 composites, the introduction of the TiC hard phase could improve the hardness of the Ti3SiC2 phase and prepare high hardness, high toughness and self-lubricating materials. In this study, elementary Ti, Si and graphite powders in the molar ratio of 3:1+x:2 were used as starting powders, a small amount of Al powder was added as a sintering aid, and spark sintering technology was used to sinter in the temperature range of 1373 to 1673 K at 50 MPa in vacuum. The reacted phases were identified by X-ray diffraction, and microstructure characteristics were observed. The formation mechanism of TiC-Ti3SiC2 composites was investigated based on the sintering behavior of the elemental powders during spark sintering. Pure TiC-Ti3SiC2 composites could be prepared from Ti, Si, graphite powders and Al at a molar ratio of 3:1.1:2:0.3 at 1573 K with a holding time of 0.9 ks. In conclusion, dual phase consist of TiC and Ti3SiC2 composite could be synthesized through in-situ reaction by adjusting process parameters such as sintering temperature, holding time and the content of Si and Al in element blending method. [doi:10.2320/***-MC2024008] ©2025 The Japan Institute of Metals and materials.

关键词： Titanium carbide

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Tailoring BaCe_(0.7)Zr_(0.1)(Dy_(0.1)|Yb_(0.1))_(0.2)O_(3-δ)electrolyte through strategic Cu doping for low temperature proton conducting fuel cells:Envisioned theoretically and experimentally

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Journal of Energy Chemistry 2025年第2期101卷 692-701,I0015页

作者： Zaheer Ud Din Babar Muhammad Bilal Hanif Yan'an Li Wan-Ting Wang Hanchen Tian Cheng-Xin Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049ShaanxiChina Department of Inorganic Chemistry Faculty of Natural SciencesComenius University Bratislava84215 BratislavaSlovakia

This study addresses the challenge of high sintering temperatures in proton-conducting fuel cells(PCFCs)with BaCeO_(3)-doped *** demonstrate that 1 mol%copper(Cu)doping at the B-site of BaCe_(0.7)Zr_(0.1)(Dy_(0.1)|Yb_(0.1))_(0.2)O_(3-δ)(BCZDYb)improves sintering behavior,enabling densification at1400℃.However,Cu doping disrupts stoichiometry,creating barium vacancies and reducing protonaccepting cations,affecting overall *** mechanism is confirmed through density functional theory(DFT)calculations and various experimental techniques,including crystal structure analysis using X-ray diffraction(XRD)and morphology and elemental analysis via field emission scanning electron microscopy(FESEM)and energy-dispersive X-ray spectroscopy(EDS).Electrochemical measurements are performed using the electrochemical impedance spectroscopy(EIS).The ionic conductivity of1 mol%Cu-doped BCZDYb(BCZDYb-1)is 1.49×10^(-2)S cm^(-1)at 650℃,which is~3.58 times higher than that of BCZDYb sintered at 1200℃.The BCZDYb-1 exhibits~16 times higher grain boundary conductivity when sintered at 1400℃,compared to undoped *** single cell employing BCZDYb-1 as the electrolyte achieved a power density of~606 mW cm^(-2)at 550℃.These results indicate that a controlled amount of Cu doping can enhance densification while maintaining high ionic co nductivity,making it suitable for practical applications in PCFCs operating at lower temperatures.

关键词： Proton conducting fuel cells(PCFCs) Sintering Densification Cu-doping Electrical conductivity BaCe_(0.7)Z_(0.1)(Dy_(0.1)/Yb_(0.1))_(0.2)O_(3-δ)(BCZDYb)

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Process parameter optimization for directed laser deposition of hot work tool steel Dievar

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International Journal of Advanced Manufacturing Technology 2025年第3期138卷 1129-1142页

作者： Belsvik, Marius Aga Hansen, Vidar Department of Mechanical and Structural Engineering and Materials Science University of Stavanger Stavanger4021 Norway Kverneland Group Operations Norway as Klepp4353 Norway

Tool steel utilized in hot work applications are prone to costly and time-consuming maintenance repair due to wear generated on the tool surface from static and dynamic high temperature loading during the production processes. Traditionally, the repair is mainly done by subtractive machining of the tool profile. Implementation of an additive manufacturing technology such as directed laser deposition can greatly reduce maintenance time by targeting specifically the worn areas of the tool surface. In the presented work, a commercially available hybrid additive manufacturing and computer numerical control system is used to deposit a powdered hot work tool steel called Dievar. The central composite design is used in the experimental setup to optimize the most influential input parameters;powder feed rate, traverse speed, and laser power by analyzing single track geometry. The presented process window produced defect free parts without the need for preheating, Applying a powder feed rate of 6.5 g/min, traverse speed of 550 mm/min, and laser power of 1500 W, yielding an average as-built hardness of 610 HV0.5 while retaining the required pre-hardened properties in the heat-affected zone in the substrate, with a minor hardness reduction of 4–5% post-deposition. Additionally, the research revealed that the established boundary conditions for aspect ratio and dilution is not an absolute requirement to achieve a fully dense part without lack of fusion or cracks. Engineers working in the field of additive manufacturing may use the presented method to find optimal process parameters and qualify the implementation of directed laser deposition in their industry, avoiding a unnecessarily large selection of samples for testing and thus saving time and resources. © The Author(s) 2025.

关键词： Hot working

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Liquid Metal Containing Fiber-Reinforced Composites for Thermal Conductivity Enhancement

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Applied Composite materials 2025年 1-11页

作者： Rojas Cardenas, Angie D. Marconnet, Amy M. Davis, Chelsea S. School of Materials Engineering Purdue University West LafayetteIN47907 United States School of Mechanical Engineering Purdue University West LafayetteIN47907 United States Department of Mechanical Engineering University of Delaware NewarkDE19716 United States Department of Materials Science and Engineering University of Delaware NewarkDE19716 United States

Increasing power density and power consumption in electronic devices necessitate heat-dissipating components with high in-plane and cross-plane thermal conductivity to prevent overheating and enhance performance and reliability. Traditionally, polymer composites are made by incorporating rigid, high thermally conductive fillers within the polymer matrix. However, the filler loadings required to achieve significant thermal conductivity enhancement can impact the mechanical properties of the material system, often making them significantly more rigid or brittle than the base polymer. In this study, we developed a method to incorporate an ultra-high molecular weight polyethylene (UHMWPE) three-dimensional fiber mat and eutectic gallium indium alloy (EGaIn) liquid metal into an epoxy matrix. We integrated in-plane and cross-plane thermal conductivity measurements with flexural modulus assessments to understand the impact of the high thermal conductivity fillers on the thermal and mechanical response of the material. This approach enhances both the in-plane and cross-plane thermal conductivity of the composite, achieving thermal conductivities three times higher in the cross-plane direction and six times higher in the in-plane direction compared to the base polymer. Moreover, mechanical characterization reveals that the mechanical performance of the composite is comparable to that of a fiber-reinforced polymer composite, and the incorporation of liquid metal does not significantly impact stiffness, even at high filler loadings. This work demonstrates the potential of strategic composite design to achieve polymeric materials with optimized thermal-mechanical coupling. These new materials offer a solution to the challenges posed by higher power consumption in electronics, providing improved heat dissipation capabilities for more reliable devices. © The Author(s) 2025.

关键词： Indium alloys

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Microstructural evolution and its influence on the wear resistance of a laser directed energy deposited Ni-based single crystal superalloy

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材料科学技术（英文版） 2025年第2期205卷 127-138页

作者： Chenyu Ren Kai Chen Jingjing Liang R.Lakshmi Narayan Upadrasta Ramamurty Jinguo Li Center for Advancing Materials Performance from the Nanoscale(CAMP-Nano) State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an 710049China Superalloys Division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Materials Science and Engineering Indian Institute of TechnologyDelhiNew Delhi 110016India School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore

The wear behavior of Ni-based single crystal(NBSC)superalloy SRR99 fabricated by laser-directed energy deposition(LDED)is investigated and compared with that of its cast *** γ'precipitate size in the latter is＞400 nm,that in the former is an order of magnitude *** sliding wear tests reveal that the wear rate and coefficient of friction of the LDED alloy are 75％and 20％lower than that of its cast counterpart,*** transmission electron microscopy investigation of the wear-tested cast alloy indicates that there is orientation change and formation of nanoscale grains only at the top layer of the worn surface,whereas regions below undergo moderate plastic deformation via dislocation *** contrast,the sub-surface of the worn LDED alloy has a graded microstructure,with a composite of NiO/γ-Ni on the top,γ'free nano-grains in the middle,and a highly deformed nanoscale layer at the *** improved wear behavior of the LDED alloy is attributed to its higher dislocation density,finer γ'precipitates,and the formation of this graded ***,a detailed description of mechanisms that lead to the formation of this unique graded microstructure is provided.

关键词： In-situ formed gradient nanostructure Enhanced wear resistance Laser-directed energy deposition additive manufacturing Ni-based single crystal superalloys Plastic deformation

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Ultrahigh Energy and Power Density in Ni-Zn Aqueous Battery via Superoxide-Activated Three-Electron Transfer

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Nano-Micro Letters 2025年第4期17卷 63-76页

作者： Yixue Duan Bolong Li Kai Yang Zheng Gong Xuqiao Peng Liang He Derek Ho School of Mechanical Engineering State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground EngineeringSichuan UniversityChengdu 610065People’s Republic of China Department of Materials Science and Engineering City University of Hong KongKowloonHong Kong 999077People’s Republic of China Hong Kong Centre for Cerebro-Cardiovascular Health Engineering Hong Kong Science ParkHong Kong 999077People’s Republic of China School of Mechanical Engineering Sichuan UniversityChengdu 610065People’s Republic of China

Aqueous Ni-Zn microbatteries are safe,reliable and inexpensive but notoriously suffer from inadequate energy and power ***,we present a novel mechanism of superoxide-activated Ni substrate that realizes the redox reaction featuring three-electron transfers(Ni↔Ni3+).The superoxide activates the direct redox reaction between Ni substrate and KNiO_(2)by lowering the reaction Gibbs free energy,supported by in-situ Raman and density functional theory *** prepared chronopotentiostatic superoxidation-activated Ni(CPS-Ni)electrodes exhibit an ultrahigh capacity of 3.21 mAh cm^(-2)at the current density of 5 mA cm^(-2),nearly 8 times that of traditional one-electron processes *** under the ultrahigh 200 mA cm^(-2)current density,the CPS-Ni electrodes show 86.4%capacity retention with a Columbic efficiency of 99.2%after 10,000 *** CPS-Ni||Zn microbattery achieves an exceptional energy density of 6.88 mWh cm^(-2)and power density of 339.56 mW cm^(-2).Device demonstration shows that the power source can continuously operate for more than 7 days in powering the sensing and computation intensive practical application of photoplethysmographic waveform *** work paves the way to the development of multi-electron transfer mechanisms for advanced aqueous Ni-Zn batteries with high capacity and long lifetime.

关键词： Superoxide Multiple electron transfer Ni aqueous battery AIoT power source Wearable health monitoring

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Fabrication of bamboo-inspired continuous carbon fiber-reinforced SiC composites via dual-material thermally assisted extrusion-based 3D printing

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材料科学技术（英文版） 2025年第5期208卷 92-103页

作者： Sai Li Haitian Zhang Zhongliang Lu Fusheng Cao Ziyao Wang Yan Liu Xiaohui Zhu Shuai Ning Kai Miao Shaoyu Qiu Dichen Li State Key Laboratory for Manufacturing Systems Engineering School of Mechanical EngineeringXi'an Jiaotong UniversityXi'an 710049China State Key Laboratory for Manufacturing Systems Engineering School of Mechanical EngineeringXi'an Jiaotong UniversityXi'an 710049China School of Intelligent Manufacturing Modern Industry Xinjiang UniversityUrumqi 830046China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610213China

Ceramic matrix composites(CMCs)structural components encounter the dual challenges of severe mechanical conditions and complex electromagnetic environments due to the increasing demand for stealth technology in aerospace *** address various functional requirements,this study integrates a biomimetic strategy inspired by gradient bamboo vascular bundles with a novel dual-material 3D print-ing *** distinct bamboo-inspired structural configurations Cf/SiC composites are designed and manufactured,and the effects of these different structural configurations on the CVI process are *** method is utilized to characterize the relationship between interface bonding strength and mechanical *** results reveal that the maximum flexural strength and fracture toughness reach 108.6±5.2 MPa and 16.45±1.52 MPa m1/2,respectively,attributed to the enhanced crack propagation resistance and path caused by the weak fiber-matrix ***,the bio-inspired configuration enhances the dielectric loss and conductivity loss,exhibiting a minimum reflection loss of-24.3 dB with the effective absorption band of 3.89 *** work introduces an innovative biomimetic strategy and 3D printing method for continuous fiber-reinforced ceramic composites,expanding the ap-plication of 3D printing technology in the field of CMCs.

关键词： 3D printing Cf/SiC composites mechanical properties Electromagnetic wave absorption

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Evolution of microstructures during isothermal annealing in hot-rolled Al-Mn alloys

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Keikinzoku/Journal of Japan Institute of Light Metals 2025年第3期75卷 137-143页

作者： Torigoe, Shoma Nakashima, Yosuke Tsuzuki, Yusho Takata, Ken Ikeda, Ken-Ichi Ii, Seiichiro Department of Mechanical Engineering Daido University 10-3 Takiharucho Minami-ku Aichi Nagoya-shi457-8530 Japan Department of Mechanical Engineering Daido University Aichi Nagoya-shi Japan Division of Materials Science and Engineering Faculty of Engineering Hokkaido University Hokkaido Sapporo-shi Japan Ibaraki Tsukuba-shi Japan

Effect of annealing in hot-rolled Al-Mn alloys on evolution of microstructures was investigated using hardness measurement, electrical-resistivity measurement, backscattered electron images, and its image analysis. Electrical resistivity with annealing time exhibited that residual content of solute Mn and Fe atoms remained in hot-rolled alloys, and that their number was decreased during annealing. Analysis of backscattering electron image of scanning electron microscopy provided that a lot of precipitates grew by consumption of such solute atoms. We considered that the growth of precipitates during isothermal annealing affect recovery and recrystallization and then hardness behavior. © 2025 The Japan Institute of Light Metals.

关键词： Manganese alloys

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