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Tailoring microstructure evolution and mechanical properties of a high-performance alloy steel through controlled thermal cycles of a direct laser depositing process

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China Foundry 2021年第5期18卷 463-473页

作者： Shi-yun Dong Xuan Zhao Shi-xing Yan yao-hui lü Xiao-ting liu Yu-xin liu Peng He Bin-shi Xu National Key laboratory for Remanufacturing Army Academy of Armored ForcesBeijing 100072China State Key laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Direct laser deposition(DlD),as a popular metal additive manufacturing process,shows advantages of technical flexibility and high efficiency to gain a high-performance alloy steel ***,during the processing of DlD,the deposited steel layer is affected by the subsequent layer *** DlD block shows different microstructure and mechanical properties at the bottom,middle and top of the deposited *** date,there are few research works about the effects of inter-layer interval time and laser power on the microstructure evolution and mechanical properties of the deposited *** this study,the idle time and laser power layer by layer during DlD of 12CrNi2 steel were controlled to cause the deposited layers to maintain a high cooling rate,while the bottom deposited layer was subjected to a weak tempering *** show that a high proportion of martensite is produced,which improves the strength of the deposited *** the laser scanning strategy of laser power 2,500 W,scanning velocity 5 mm·s^(-1),powder feeding rate 11 g·min^(-1),overlap rate 50%,and a laser power difference of 50 W and a 2 min interval,the tensile strength of the deposited layer of 12CrNi2 steel is in the range of 873-1,022 MPa,and the elongation is in the range of 16.2%-18.9%.This study provides a method to reduce the tempering effect of the subsequent deposition layers on the bottom layers,which can increase the proportion of martensite in the low-alloy high-strength steel,so as to improve the yield strength of the alloy steel.

关键词： alloy steel direct laser deposition thermal cycles microstructure evolution mechanical properties

Microstructure and mechanical properties of heat affected zone in multi-pass GMA welded Al-Zn-Mg-Cu alloy

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Transactions of Nonferrous Metals Society of China 2019年第11期29卷 2273-2280页

作者： Jia-liang ZHOU Feng-yuan SHU Hong-yun ZHAO yao-hui lü Yu-xin lIU Peng HE Shandong Provincial Key laboratory of Special Welding Technology Harbin Institute of Technology at WeihaiWeihai 264209China National Key laboratory of Remanufacturing Beijing 100072China State Key laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Microstructure and mechanical properties of the heat affected zone(HAZ)in multi-pass gas metal arc(GMA)welded Al Zn Mg Cu alloy plates were investigated,based upon which the mechanical anisotropy and fracture mechanism were *** microstructure and composition were analyzed by scanning electron microscope(SEM)and energy dispersive spectroscope(EDS).X-ray diffractometer(XRD),transmission electron microscope(TEM)and selective area electron diffraction(SAED)were used to analyze the phase *** distribution of microhardness was identified as gradual transition and tensile strength had a tendency to decrease first and then *** distribution of nano-sizedη(MgZn2)particles in theα(Al)matrix and Al2MgCu phase determined the tensile performances along the thickness direction and led to the formation of ductile/brittle composite fracture in the *** continuous distribution of Al2MgCu phase in the strip intergranular precipitates gave birth to premature cracks and the brittle fracture *** precipitated particles coarsening also led to the deterioration of mechanical properties.

关键词： Al-Zn-Mg-Cu alloy heat affected zone microstructure mechanical properties ductile/brittle composite fracture

An Efficient Boron Source Activation Strategy for the low‑Temperature Synthesis of Boron Nitride Nanotubes

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Nano-Micro letters 2025年第1期17卷 548-558页

作者： Ying Wang Kai Zhang liping Ding liyun Wu Songfeng E Qian He Nanyang Wang hui Zuo Zhengyang Zhou Feng Ding Yue Hu Jin Zhang Yagang yao National laboratory of Solid State Microstructures College of Engineering and Applied SciencesJiangsu Key Laboratory of Artificial Functional Materialsand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093People’s Republic of China School of Electronic Information and Artificial Intelligence Shaanxi University of Science&TechnologyXian 710000People’s Republic of China College of Bioresources Chemical and Materials Engineering Shaanxi University of Science&TechnologyXian 710000People’s Republic of China Key laboratory of Carbon Materials of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325000People’s Republic of China Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518000People’s Republic of China College of Chemical and Molecular Engineering Peking UniversityBeijing 100871People’s Republic of China

lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their *** primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid *** this study,we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO–B *** approach can be adopted to form various low-melting-point AM–Mg–B–O growth *** growth systems have improved catalytic capability and reactivity even under low-temperature conditions,facilitating the synthesis of BNNTs at temperatures as low as 850℃.In addition,molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN *** findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs.

关键词： Boron nitride nanotubes low-temperature Boron activation Density functional theory

FEM modeling of softened base metal in narrow-gap joint by CMT+P MIX welding procedure

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Transactions of Nonferrous Metals Society of China 2014年第6期24卷 1830-1835页

作者：舒凤远吕耀辉刘玉欣徐富家孙哲何鹏徐滨士哈尔滨工业大学先进焊接与连接技术国家重点实验室哈尔滨150001 装甲兵工程学院再制造技术重点实验室北京100072

A required finite element method（FEM） model applicable for narrow gap CMT and CMT＋P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire feeding pulses and heat input pulses was supposed under the conduction of equivalent *** method together with composed double-ellipse heat sources was included in the *** model was employed in the investigation of thermal cycling and the identification of the softened zone of AA7A52 base ***-frequency behavior emerged in the form of low-cooling rate sects,which were not expected under experimental *** softened zone including the quenched zone and averaging zone of the base plate was much wider internal the base plate than that close to the *** reliability of the predictions in thermal cycling was supported by infrared imaging test results of the thermal cycle process.

关键词： cold metal transferring finite element method equivalent input low-cooling rate sects softened zone

Prediction of vulnerable zones based on residual stress and microstructure in CMT welded aluminum alloy joint

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Transactions of Nonferrous Metals Society of China 2015年第8期25卷 2701-2707页

作者：舒凤远田泽吕耀辉贺文雄吕飞洋林建军赵洪运徐滨士哈尔滨工业大学(威海)材料科学与工程学院山东省特种焊接技术重点实验室威海264209 装甲兵工程学院再制造技术国防科技重点实验室北京100072 上海交通大学材料激光加工与改性上海市重点实验室上海200240

Numerical simulation and experimental results were employed for the identification of the most vulnerable zones in three-pass cold-metal-transferring （CMT） welded joint. The residual stress distribution in the joint was predicted by finite element （FE） method, while the structural morphology of distinctive zones was obtained through metallographic experiments. The highest principal stress made the symmetric face of the joint most sensitive to tensile cracks under service conditions. Whereas, the boundaries between the weld seam and the base plates were sensitive to cracks because the equivalent von Mises stress was the highest when the first interpass cooling was finished. The third weld pass and the inter-pass remelted zones exhibited the modest mechanical performances as a result of the coarse grain and coarse grain boundary, respectively. The most vulnerable zones were regarded to be the crossed parts between the zones identified by numerical and experimental methods.

关键词： aluminum alloy vulnerable zone cold-metal-transferring welded joint residual stress microstructure morphology

Synthesis,Characterization and Structure of Chiral Amino Acids and Their Corresponding Amino Alcohols with Camphoric Backbone

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Chinese Journal of Structural Chemistry 2006年第10期25卷 1243-1249页

作者： QIAN hui-Fen HUANG Wei lI hui-hui yao Cheng College of Sciences Nanjing University of Technology Nanjing 210009 China State Key laboratory of Coordination Chemistry Coordination Chemistry Institute School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 China

Chiral amino acids and their corresponding amino alcohols bearing camphoric backbone were prepared from D-（＋）-camphoric imide and characterized by infrared, elemental analysis, ESI-MS, and NMR measurements. Among them, one intermediate （1S,3R）-3-amino-2,2,3- trimethyl cyclopentane-1-carboxylic acid hydrochloride 3 was structurally elucidated by X-ray diffraction techniques. Versatile intermolecular hydrogen bonding interactions observed in its packing structure result in a two-dimensional framework.

关键词： chiral amino acids and amino alcohols (1S,3R)-3-amino-2,2,3-trimethyl-cyclopentane-1-carboxylic acid hydrochloride hydrogen-bonding interactions crystal structures

Immunomodulation of artemisinin and its derivatives

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Science Bulletin 2016年第18期61卷 1399-1406页

作者： Wenbo yao Feng Wang hui Wang Key laboratory of Food Safety Research Institute for Nutritional Sciences Shanghai Institutes for Biological SciencesChinese Academy of Sciences University of Chinese Academy of Sciences School of life Science and Technology ShanghaiTech University Key laboratory of Food Safety Risk Assessment Ministry of Health

In the 1970 s, artemisinin(‘‘qinghaosu'' in Chinese), a sesquiterpene lactone with an unusual peroxide bridge, was isolated from Artemisia annua l. It showed promising antimalarial activity, particularly by eliminating parasites resistant to chloroquine. For more than 30 years,artemisinin has contributed to worldwide health as a new type of antimalarial drug. Artemisinin and its analogs, such as dihydroartemisinin, artemether, artesunate, artemiside,artemisone, and arteether, possess not only potent antimalarial activity but also anti-viral, antifungal, anticancer,and anti-inflammatory properties. In this review, we discuss the current understanding of how artemisinin and its analogs affect the immune system and immune-related diseases.

关键词： Artemisinin Immune system Immune-related diseases Macrophage T-cell B-cell

IMAGE SEGMENTATION BY PIECEWISE CONSTANT MUMFORD-SHAH MODEl WITHOUT ESTIMATING THE CONSTANTS

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Journal of Computational Mathematics 2006年第3期24卷 435-443页

作者： Xue-cheng Tai Chang-hui yao CIPR Department of Mathematics University of Bergen Norway Department of Mathematics University of Bergen Norway

In this work, we try to use the so-called Piecewise Constant level Set Method （PClSM） for the Mumford-Shah segmentation model. For image segmentation, the Mumford-Shah model needs to find the regions and the constant values inside the regions for the segmen- tation. In order to use PClSM for this purpose, we need to solve a minimization problem using the level set function and the constant values as minimization variables. In this work, we test on a model such that we only need to minimize with respect to the level set function, i.e., we do not need to minimize with respect to the constant values. Gradient descent method and Newton method are used to solve the Euler-lagrange equation for the minimization problem. Numerical experiments are given to show the efficiency and advantages of the new model and algorithms.

关键词： PClSM Image Segmentation Mumford-Shah model.

Chemically synthesizing exchange-coupled SmCo_(5)/Sm_(2)Co_(17) nanocomposites

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Rare Metals 2021年第3期40卷 575-581页

作者： yao-hui Xu Qiang Jiang Kun li Zhen-hui Ma School of Physics and Electronic Engineering Laboratory for Functional MaterialsLeshan Normal UniversityNanjing 211189China Jiangsu Key laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments School of Mechanical EngineeringSoutheast UniversityNanjing 211189China College of Materials Science and Engineering Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing 100124China Department of Chemistry Brown UniversityProvidenceRI 02912USA

A new strategy to chemically synthesize exchange-coupled SmCo_(5)/Sm_(2) Co_(17) nanocomposites by in situ decomposition of SmCox(5 详细信息

A new strategy to chemically synthesize exchange-coupled SmCo_(5)/Sm_(2) Co_(17) nanocomposites by in situ decomposition of SmCox(5le crystal nanoparticles by Ca under the protection of CaO,showing a high coercivity of 2.85 T and saturation magnetization(Ms)of 0.0671 A·m^(2)·g^(-1).By changing the Sm/Co to 1:4.5,1:4.8 and 1:5.2,SmCo_(5)/Sm_(2) Co_(17) nanocomposites with different proportions were acquired using the same *** to the in situ decomposition of SmCo_(x) intermediate,the small size(both of their size less than 10 nm)and uniform phase distribution were achieved in our ***,the as-prepared nanocomposites display a strong exchange-coupling *** a consequence,SMCo_(5)/Sm_(2)Co_(17)(Sm/Co=1:5.2)exhibits a coercivity of 1.23 T and enhanced M7 T(magnetization at 7 T)of 0.0812 A·m^(2)·g^(-1),increasing by 21%than pure SmCo_(5).Our synthesis provides a new protocol to prepare exchange-coupled high-performance nanocomposites.

关键词： SmCo_(5) Nanocomposites Exchange coupling Coercivity