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Morphological Heredity of Intermetallic Nb_(5)Si_(3)Dendrites in Hypereutectic Nb-Si Based Alloys via Non-Equilibrium Solidification

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 393-400页

作者： Yueling Guo Lina Jia wenjun lu Hu Zhang School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Research Center of Light‑alloy Materials Frontier Institute of Science and Technology InnovationBeihang UniversityBeijing 100191China Max-Planck-Institut für Eisenforschung Max‑Planck‑Straße 140237 DüsseldorfGermany

For hypereutectic Nb-Si based alloys,primary Nb_(5)Si_(3)phases typically grow in a faceted mode during equilibrium or near-equilibrium solidification,which damages the ductility and *** address this issue,here we artificially manipulate the growth morphology of Nb_(5)Si_(3)using electron beam surface melting(EBSM)and subsequent annealing *** show that such a non-equilibrium solidification pathway enables the transition from faceted growth to non-faceted dendritic growth of Nb_(5)Si_(3),along with evident microstructure refinement,generation of metastableβ-Nb_(5)Si_(3)phases and elimination of chemical *** transformation fromβ-Nb_(5)Si_(3)toα-Nb_(5)Si_(3)and Nb solid solution(Nbss)particles is triggered by the annealing treatment at 1450°C for 5 ***,we find the annealing-mediated formation of inherited Nb_(5)Si_(3)dendrites that maintain the dendritic morphology of the original as-solidifiedβ-Nb_(5)Si_(3)*** work thus provides a feasible routine to obtain thermally stable and refinedα-Nb_(5)Si_(3)dendrites in hypereutectic Nb-Si based alloys.

关键词： Nb-Si alloy Intermetallics Nb_(5)Si_(3) Rapid solidification Dendritic growth

Shear instability in heterogeneous nanolayered Cu/Zr composites

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Journal of Materials Science & Technology 2022年第10期105卷 81-91页

作者： Jianjun Li Feng Qin Dingshun Yan wenjun lu Jiahao Yao School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ultrastrong nanolayered metallic composites are usually subjected to low ductility due to plastic instability during *** we investigated the shear instability of a newly designed heterogeneous nanolayered Cu/Zr composites by *** heterogeneity in size was generated by inserting a few thin Cu-Zr bilayers with an individual layer thickness of 2.5-10 nm into the interface region of the Cu/Zr layered composites with an individual layer thickness of 100 *** microindentation tests showed that multiple shear bands appeared in the heterogeneous composite with one bilayer,whereas only a single shear band was formed in that with two or three *** importantly,the layer strain in the multi-shear band region is much smaller than that in the single-shear band *** example,the strain of the 100 nm layers within the shear band in the composite with one 10 nm bilayer could reach as low as 2.8,which was less than half of that in the composite with three 10 nm bilayers,i.e.,*** fndings demonstrated that strain delocalization can be achieved through shear band multiplication if an appropriate number of thin bilayers were used as interlayers in the 100 nm Cu/Zr ***,compared with the homogeneous composite with an individual layer thickness of 100 nm and the bimodal composite which is composed of alternating one 100 nm Cu-Zr bilayer and two 10 nm CuZr bilayers,the heterogeneous composite with one bilayer displayed a higher strength(2.15 GPa)and a favorable resistance to strain localization.

关键词： Nanolayered metallic composites Sputtering Microindentation Shear band Strain delocalization

Modeling and Prediction of Fatigue Properties of Additively Manufactured Metals

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Acta Mechanica Solida Sinica 2023年第2期36卷 181-213页

作者： Wei Tang Ziming Tang wenjun lu Shuai Wang Min Yi State Key Lab of Mechanics and Control of Mechanical Structures&Institute for Frontier Science&Key Lab for Intelligent Nano Materials and Devices of Ministry of Education&College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics(NUAA)Nanjing 210016China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China

Additive manufacturing(AM)has emerged as an advanced technique for the fabrication of complex near-net shaped and lightweight metallic parts with acceptable mechanical *** strength of AM metals has been confirmed comparable or even superior to that of metals manufactured by conventional processes,but the fatigue performance is still a knotty issue that may hinder the substitution of currently used metallic components by AM counterparts when the cyclic loading and thus fatigue failure *** essential complements to high-cost and time-consuming experimental fatigue tests of AM metals,models for fatigue performance prediction are highly *** this review,different models for predicting the fatigue properties of AM metals are summarized in terms of fatigue life,fatigue limit and fatigue crack growth,with a focus on the incorporation of AM characteristics such as AM defect and processing parameters into the *** predicting the fatigue life of AM metals,empirical models and theoretical models(including local characteristic model,continuum damage mechanics model and probabilistic method)are *** terms of fatigue limit,the introduced models involve the Kitagawa–Takahashi model,the Murakami model,the El-Haddad model,*** modeling the fatigue crack growth of AM metals,the summarized methodologies include the Paris equation,the Hartman-Schijve equation,the NASGRO equation,the small-crack growth model,and numerical *** of these models for AM metals are similar to those for conventionally processed materials,but are modified and pay more attention to the AM ***,an outlook for possible directions of the modeling and prediction of fatigue properties of AM metals is provided.

关键词： Additive manufacturing Fatigue properties Metals Modeling and prediction Microstructure

Dual-Mode Resonant Sectorial Monopole Antenna with Stable Backfire Gain

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Chinese Journal of Electronics 2024年第6期33卷 1478-1486页

作者： Feiyan JI Heng ZHANG Xiuqiong XING wenjun lu Lei ZHU Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Key Laboratory of Wireless Sensor Network & Communication Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Department of Electrical and Computer Engineering Faculty of Science and Technology University of Macau

A novel design approach to wideband, dual-mode resonant monopole antenna with stable, enhanced backfire gain is advanced. The sectorial monopole evolves from a linear, 0.75-wavelength electric prototype monopole under wideband dual-mode resonant operation. As theoretically predicted by the two resonant modes TE3/5,1and TE9/5,1within a 150° radiator, the operation principle is revealed at first. As have been numerically demonstrated and experimentally validated at 2.4-GHz band, the designed antenna exhibits a wide impedance bandwidth over 90.1%（i.e., 2.06–5.44 GHz）, in which the stable gain bandwidth in the backfire,-x-direction（θ = 90°, φ = 180°） with peak value of 3.2 dBi and fluctuation less than 3 dB is up to 45.3%（i.e., 3.74–5.44 GHz）. It is concluded that the stable wideband backfire gain frequency response should be owing to the high-order resonant mode in the unique sectorial monopole antennas.

关键词： Fluctuations Azimuth Prototypes Metals Resonance Frequency measurement Broadband antennas Impedance Gain Wideband

Dual Radial-Resonant Wide Beamwidth Circular Sector Microstrip Patch Antennas

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Chinese Journal of Electronics 2023年第4期32卷 710-719页

作者： MAO Xiaohui lu wenjun JI Feiyan XING Xiuqiong ZHU Lei Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Key Laboratory of Wireless Sensor Network & Communication Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Department of Electrical and Computer Engineering Faculty of Science and Technology University of Macau

In this article, a design approach to a radial-resonant wide beamwidth circular sector patch antenna is advanced. As properly evolved from a U-shaped d ipole, a prototype magnetic dipole can be fit in the radial direction of a circular sector patch radiator, with its length set as the positive odd-integer multiples of onequarter wavelength. In this way, multiple TM0m(m = 1,2,...) modes resonant circular sector patch antenna with short-circuited circumference and widened E-plane beamwidth can be realized by proper excitation and perturbations. Prototype antennas are then designed and fabricated to validate the design approach. Experimental results reveal that the E-plane beamwidth of a dual-resonant antenna fabricated on air/Teflon substrate can be effectively broadened to 128°/120°, with an impedance bandwidth of 17.4%/7.1%, respectively. In both cases, the antenna heights are strictly limited to no more than 0.03-guided wavelength. It is evidently validated that the proposed approach can effectively enhance the operational bandwidth and beamwidth of a microstrip patch antenna while maintaining its inherent low profile merit.

关键词： Geometry Patch antennas Perturbation methods Prototypes Magnetic resonance Microstrip antennas Bandwidth

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Characterization of Compositionally Complex Hydrides in a Metastable Refractory High-Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1173-1178页

作者： Jikui Liu Junhua Hou Fengchao An Bingnan Qian Christian H.Liebscher wenjun lu Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen518055China Max-Planck-Institut Für Eisenforschung Max-Planck-Straße 140237DüsseldorfGermany

Here,we study the hydride formation in a metastable Ti-33Zr-22Hf-11Ta(at.%)refractory high entropy alloy(RHEA).Deviating to non-equiatomic compositions of RHEAs promotes the formation of transformation-induced plasticity where the body-centered cubic phase transforms to hexagonal close-packed(HCP)*** is found that the phase transformation capability assists the hydride formation due to the low solubility of hydrogen within the HCP *** this study,hydrogen is charged via electrochemical polishing and the corresponding phase transformation is activated in the metastable *** newly formed HCP phase interacts with hydrogen to form a face-centered cubic hydride verified by electron energy loss *** work provides a primary exploration of the formation of compositionally complex metal hydrides in the metastable RHEAs,which are potential candidates for future hydrogen storage material design.

关键词： Refractory high entropy alloy Compositionally complex hydrides Electrochemical polishing Phase transformation Scanning transmission electron microscopy(STEM)/electron energy loss spectroscopy(EELS)

A Novel High-Entropy Amorphous Thin Film with High Electrical Resistivity and Outstanding Corrosion Resistance

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Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1537-1545页

作者： Chuang-Shi Feng Tian-Wei lu Tian-Li Wang Man-Zhen Lin Junhua Hou wenjun lu Wei-Bing Liao College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China College of Materials Science and Engineering Shenzhen UniversityShenzhen 518060China Department of Materials Science and Engineering City University of Hong KongHong Kong 999077China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China

This study explores a novel WNbMoTaV high-entropy thin film(HETF)in amorphous structure via pulsed laser deposition *** formation of amorphous structure of this high-entropy alloy is ascribed to the high cooling rate during the deposition *** HETF shows a smooth surface with a height fl uctuation of less than 13 *** film has a high electrical resistivity of~320.6μΩ·cm and a low corrosion current density of 0.088μA/cm *** corrosion resistance of the HETF at ambient temperature is superior to the conventional AISI 316 L stainless *** high electrical resistivity and excellent corrosion resistance of the HETF are mainly attributed to its chemical disorder,cocktail effect and homogeneous amorphous *** experimental phenomenon not only provides a basis for the preparation of amorphous alloy films with low glass forming ability by pulsed laser deposition system,also promotes the potential application of WNbMoTaV HETF in the microelectronic components as resistivity sensors.

关键词： High-entropy alloys Thin films Electrical resistivity Microstructures Corrosion behaviors

Landslide Damming Threats Along the Jinsha River, China

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ENGINEERING 2024年第11期42卷 326-339页

作者： Xiao, Shihao Zhang, Limin Xiao, Te Jiang, Ruochen Peng, Dalei lu, wenjun He, Xin Hong Kong Univ Sci & Technol Dept Civil & Environm Engn Hong Kong 999077 Peoples R China Hong Kong Univ Sci & Technol Shenzhen Hong Kong Collaborat Innovat Res Inst Shenzhen 518000 Peoples R China Chengdu Univ Technol State Key Lab Geohazard Prevent & Geoenvironm Prot Chengdu 610000 Peoples R China

The 2280 km long Jinsha River has been blocked at least four times in the past 30 years. A landslide damming hazard chain can endanger communities and infrastructures hundreds of kilometers downstream from the damming site in alpine gorges. Past damming events have resulted in severe consequences, demanding a thorough assessment of damming threats along the entire Jinsha River. This study digitizes the Jinsha River and visualizes its topographic, tectonic, hydrologic, and climate characteristics in detail. A two-stage full-probability method is proposed for assessing the damming threats along this river, making it possible to identify potential damming hotspots and high-priority zones for hazard mitigation. It is found that the upper reach of the Jinsha River poses the greatest damming threat, and the threat level gradually decreases downstream. Approximately 33.4%, 36.7%, 20.5%, and 9.4% of the entire length of the Jinsha River are classified as low, moderate, high, and very high threat levels, respectively. Compared with existing hydropower projects, future projects in the upper reach are more likely to be exposed to landslide damming. We highlight the value of basin-scale spatial threat analysis and envisage that our findings will promote more targeted local-scale risk assessments for potential damming hotspots. These outcomes provide the basis for managing the risks of river damming and hydropower infrastructure along the Jinsha River. (c) 2024 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Landslide dam Landslides Jinsha River Risk analysis Hydropower

Lithology Classification Based on Set-Valued Identification Method

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Journal of Systems Science & Complexity 2022年第5期35卷 1637-1652页

作者： LI Jing WU Lifang lu wenjun WANG Ting KANG Yu FENG Deyong ZHOU Hansheng Department of Automation University of Science and Technology of ChinaHefei 230027China Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100190China Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China Shengli Geophysical Research Institute SINOPEC GroupDongying 257022China Institute of Artificial Intelligence Hefei Comprehensive National Science CenterHefei 230088China

Lithology classification using well logs plays a key role in reservoir *** paper studies the problem of lithology identification based on the set-valued method(SV),which uses the SV model to establish the relation between logging data and lithologic types at a certain depth *** particular,the system model is built on the assumption that the noise between logging data and lithologic types is normally distributed,and then the system parameters are estimated by SV method based on the existing identification *** logging data of Shengli Oilfield in Jiyang Depression are used to verify the effectiveness of SV *** results indicate that the SV model classifies lithology more accurately than the Logistic Regression model(LR)and more stably than uninterpretable models on imbalanced ***,the Macro-F1 of the SV models(i.e.,SV(3),SV(5),and SV(7))are higher than 85%,where the sandstone samples account for only 22%.In addition,the SV(7)lithology identification system achieves the best stability,which is of great practical significance to reservoir exploration.

关键词： DT lithology classification LR RF set-valued model SVM