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Strain rate sensitivity of a 1.5 GPa nanotwinned steel

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Journal of Iron and Steel Research(International) 2021年第11期28卷 1352-1356页

作者： R.D.liu y.z.li l.lin C.P.Huang z.H.Cao m.X.Huang Iron and Steel Research Institute Ansteel GroupAnshan 114021LiaoningChina Department of mechanical Engineering The University of Hong KongHong Kong 999077China

Two distinct regimes of strain rate sensitivity on yield strength are found in a high-strength nantwinned *** yield strength increases from 1410 to 1776 mPa when the strain rate increases from 10–3 to 1400 *** is proposed from the measured small activation volume that the yielding of the nanotwinned steel at higher strain rates is governed by the dislocation bowing out from the carbon *** lower strain rates,however,the yielding is controlled by the continuous re-pinning of dislocations due to the fast diffused carbon atoms,which leads to the relative insensitivity of yield strength to the strain rate.

关键词： Nanotwinned steel Strain rate sensitivity Hokinson tensile bar Twinning Twinning-induced plasticity steel

Influence and mechanism of solar radiation intensity on the interdecadal variability of strong meiyu events during historical periods

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Science China Earth Sciences 2023年第2期66卷 408-416页

作者： liulin WANG liang NING Kefan CHEN mi yAN Jian lIU zhengyu lIU yanmin QIN Jiao XUE Chuxin lI Key laboratory for Virtual Geographic Environment Ministry of Education/State Key Laboratory Cultivation Base of Geographical Environment Evolution of Jiangsu Province/Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application/School of GeographyNanjing Normal UniversityNanjing210023China Open Studio for the Simulation of Ocean-Climate-Isotope Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao266237China Climate System Research Center Department of GeosciencesUniversity of MassachusettsAmherst01003USA State Key laboratory of loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an710061China Department of Geography The Ohio State UniversityColumbusOH43210USA

most recent studies on meiyu over the middle and lower reaches of the yangtze River(mlRyR)have focused on its interannual variability or the mechanism of certain abnormal *** influence and physical mechanism of solar radiation intensity on the interdecadal frequency of strong meiyu events over the mlRyR during historical periods were investigated using reconstructed precipitation data,reconstructed solar radiation data,and model simulation ***,according to the solar radiation intensity,the ming and Qing Dynasties(1470-1850)were divided into three periods of strong solar radiation and three periods of weak solar *** was found that during the periods of strong solar radiation,the frequency of strong meiyu events was significantly higher than that during the periods of weak solar radiation in the reconstructed precipitation data and model *** analyses show that during the periods of strong solar radiation,the Western Pacific Subtropical High(WPSH)is stronger,and the blocking highs over the middle-high-latitudes are also stronger,which is conducive to the continuous convergence of the southward cold air and the northward warm and humid air flow at the ***,a circulation spatial pattern conducive to the occurrence of strong meiyu events is then *** probability distributions of precipitation also show that,during periods of strong solar radiation,changes in circulation patterns cause the probability distribution of precipitation to shift significantly to the right,increasing the probability of strong meiyu events occurring on the right side of the probability distribution.

关键词： ming Dynasty Historical flood Strong meiyu events Solar radiation CESm-lmE

long-period grating inscription on polymer functionalized optical microfibers and its applications in optical sensing

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Photonics Research 2016年第2期4卷 45-48页

作者： z.y.Xu y.H.li l.J.Wang Joint Institute for measurement Science Tsinghua University Shanghai Institute of laser Plasma State Key laboratory of Precision measurement Technology and Instruments Tsinghua University

We demonstrated long-period grating(lPG) inscription on polymer functionalized optical microfibers and its applications in optical sensing. Optical microfibers were functionalized with ultraviolet-sensitive polymethyl methacrylate jackets and, thus, lPGs could be inscribed on optical microfibers via point-by-point ultraviolet laser exposure. For a 2 mm long microfiber lPG(mlPG) inscribed on optical microfibers with a diameter of 5.4 μm, a resonant dip of 15 d B at 1377 nm was observed. This mlPG showed a high sensitivity of strain and axial force, i.e.,-1.93 pm∕με and-1.15 pm∕μN, respectively. Although the intrinsic temperature sensitivity of the lPGs is relatively low, i.e.,-12.75 pm∕°C, it can be increased to be-385.11 pm∕°C by appropriate sealing. Benefiting from the small footprint and high sensitivity, mlPGs could have potential applications in optical sensing of strain,axial force, and temperature.

关键词： mlPG long-period grating inscription on polymer functionalized optical microfibers and its applications in optical sensing

Comparison of microstructure and mechanical behavior of Ti-35Nb manufactured by laser powder bed fusion from elemental powder mixture and prealloyed powder

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Journal of materials Science & Technology 2022年第10期105卷 1-16页

作者： J.C.Wang y.J.liu S.X.liang y.S.zhang l.Q.Wang T.B.Sercombe l.C.zhang School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia School of Engineering M050The University of Western Australia35 Stirling HighwayCrawleyPerthWA 6009Australia Northwest Institute for Nonferrous metal Research Xi’an 710016China State Key laboratory of metal matrix Composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Although different types of powder feedstock are used for additive manufacturing via laser powder bed fusion(l-PBF),limited work has attempted to directly compare the microstructure and mechanical behavior of components manufactured from those powder *** work investigated the microstructure,phase composition,melt pool morphology,and mechanical properties of a prealloyed Ti-35Nb alloy manufactured using l-PBF and compared these to their counterparts produced from elemental powder *** samples manufactured from the powder mixture are composed of randomly distributed undissolved Nb in theα/βmatrix,resulting from the unstable melt pool during the melting of the powder *** contrast,parts produced from prealloyed powder display a homogeneous microstructure withβandαphases,owing to the full melting of prealloyed powder,therefore,a more stable melt pool to achieve a homogeneous *** Ti-35Nb manufactured from prealloyed powder exhibits large tensile ductility(about 10 times that of the counterparts using mixed powder),attributed to the high homogeneity in microstructure and chemical composition,strong interface bonding,relatively low oxygen content,and the existence of a large amount ofβ*** work sheds insights into understanding the effect of powder feedstock on the melt pool stability therefore the microstructure and mechanical behavior of the resultant parts.

关键词： Titanium-niobium Powder bed fusion Additive manufacturing melt pool stability microstructure mechanical properties

The combined effects of grain and sample sizes on the mechanical properties and fracture modes of gold microwires

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Journal of materials Science & Technology 2019年第1期35卷 76-83页

作者： H.K.yang K.Cao y.Han m.Wen J.m.Guo z.l.Tan J.lu y.lu Hong Kong Branch of National Precious metals material Engineering Research Center City University of Hong Kong Department of mechanical and Biomedical Engineering City University of Hong Kong State Key laboratory of Advanced Technologies for Comprehensive Utilization of Platinum metals Sino-platinum Metals Co.Ltd Center for Advanced Structural materials City University of Hong Kong Shenzhen Research Institute

Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually *** the t/d value further decreasing(t/d mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes.

关键词： Gold microwire Wire bonding Tensile testing Grain size Hall-Petch relationship

成人肥胖早期心肌组织重塑及与区域脂肪分布和异位脂肪沉积的关系：一项前瞻性研究

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国际医学放射学杂志 2024年第2期 253-253页

作者： J.liu y.l.Qu J.li W.z.He X.y.Chen X.li 朱婉秋

摘要目的探讨成人肥胖早期左室(lV)心肌组织特征及其与区域脂肪分布和异位脂肪沉积的关系。方法前瞻性纳入49例肥胖成人[平均体质量指数(29.9±2.0)kg/m2]和44

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Two-stage double peaks ageing and its effect on stress corrosion cracking susceptibility of Al-zn-mg alloy

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Journal of materials Science & Technology 2018年第7期34卷 1250-1257页

作者： y.l.Wang H.C.Jiang z.m.li D.S.yan D.zhang l.J.Rong CAS Key laboratory of Nuclear materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences School of materials Science and Engineering University of Science and Technology of China

Different artificial two-stage ageing behaviors and their effect on stress corrosion cracking （SCC） susceptibility of AI-zn-mg alloy have been investigated. The experimental results show that two hardness peaks present on the second-stage ageing-hardening curve when the first-stage ageing is dealt with comparatively lower temperature than the conventional one. The first peak is caused by dispersive and evenly distributed G.P. zones, while η ′phases and coarsened G.P. zones contribute to the second peak. Tensile strength of experimental alloy raises 9.6% （33.2 mPa） and SCC susceptibility decreases 38.9% by applying the second peak ageing regime instead of conventional T73. AI-zn-mg alloy obtains high strength and SCC resistance due to its finely dispersive matrix precipitates （mPts）, coarsened and discontinuous grain boundary precipitates （GBPs）, as well as the narrow precipitate free zone （PFz） in the second peak ageing condition. 2017 Published by Elsevier ltd on behalf of The editorial office of Journal of materials Science ＆ Technology.

关键词： Al-zn-mg alloy Two-stage ageing Double peaks ageing Stress corrosion cracking (SCC) susceptibility Grain boundary precipitates (GBPs)

mg-Ni THIN FIlm-A POTENTIAl NEGATIVE ElECTRODE FOR NIKEl-mETAl HyDRIDE baTTery

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Acta metallurgica Sinica(English letters) 2003年第3期16卷 226-230页

作者： l.z.Ouyang C.y.Chung m.Q.zeng H.Wang m.z.u College of mechanical Engineering South China University of TechnologyGuangzhou 510641China Department of Physics and Material Science City University of Hong Kong83 Tat Chee AvenueKowloon Hong KongDepartment of Physics and Material Science City University of Hong Kong83 Tat Chee Avenue Kowloon Hong Kong College of Mechanical EngineeringSouth China University of TechnologyGuangzhou 510641ChinaCollege of Mechanical EngineeringSouth China University of TechnologyGuangzhou 510641ChinaCollege of Mechanical EngineeringSouth China University of TechnologyGuangzhou 510641China

mg-Ni thin films for nickel-metal hydride (Ni-mH) battery negative electrode were prepared on three different substrates by using magnetron sputtering with compacted Ni and mg mixture powder. The microstructure of mg-Ni thin films deposited on the glass and the Ni foil substrate respectively was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEm). The results show that the mg-Ni thin films were in amorphous structure and the composition of the thin film was homogeneous. Electrochemical measurement show the discharge capacity of the thin film negative electrode deposited on the foam Ni substrate was 284.8mAh/g in 6m alkaline electrolyte and the internal resistance was much lower than that of the electrode prepared by the ball-milled powder during the charge-discharge cycle.

关键词： magnetron sputtering mg-Ni thin film Ni-mH battery

QUANTITATIVE ANAlyTIC TECHNOlOGy OF UlTRA-HARDNESS AND WEAR RESISTENT SURFACING mATerIAl

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Acta metallurgica Sinica(English letters) 2004年第1期17卷 28-32页

作者： W.S.li B.S.Wang l.z.Feng y.Q.zhou y.m.z.ang School of matericals Science and Engineering Tianjin University Tianjin 300072 ChinaSchool of Matericals Science and Engineering Tianjin University Tianjin 300072 ChinaSchool of Matericals Science and Engineering Tianjin University Tianjin 300072 ChinaSchool of Matericals Science and Engineering Tianjin University Tianjin 300072 ChinaSchool of Matericals Science and Engineering Tianjin University Tianjin 300072 China

mathematical models between surfacing welding properties of C, Cr, mo, V, W alloy system and encode factors of alloy additives are established by test methods of advanced trial optim.z.ng technology and computer assistant design (CAD). They help to draw unitary functions and binary isoclines diagrams through which the influence of encode factorial linearity, nonlinear effect and factors interaction of alloy additives on the performances of surfacing welding can be analyzed directly and quantitatively. meanwhile, the performances of deposited metal can also be predicted according to the content of alloy additives.

关键词： surfacing materials ultra-high hardness wear resistant quantitative analysis