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Microstructural characterization and mechanical properties of(TiC+TiB)/TA15 composites prepared by an in-situ synthesis method

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China Foundry 2024年第2期21卷 168-174页

作者： zhi-yong Zhang Jiao-jiao Cheng Jia-qi Xie Shi-bing Liu Kun Shi Jun zhao Shenyang Research Institute of Foundry Co. Ltd.CAMShenyang 110022China National Key Laboratory of Advanced Casting Technologies Shenyang 110022China

Titanium matrix composites reinforced with ceramic particles are considered a promising engineering material due to their combination of high specific strength,low density,and high *** this study,the TA15-based composites reinforced with a volume fraction of 10% to 25%(TiB+TiC)were prepared using powder metallurgy and casting *** characterization and phase constitution were examined using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray diffraction(XRD).In addition,the microhardness,room temperature(RT)and high temperature(HT)tensile properties of the composites were *** revealed that the reinforcements are distributed uniformly even in the composites with a high volume of TiB and ***,as the volume fraction exceeds 15%,TiB and TiC particles become coarsening and exhibit rod-like and dendritic-like *** increases gradually from 321.2 HV for the base alloy to a maximum of 473.3 HV as the reinforcement increases to 25vol.%.Tensile test results indicate that a reinforcement volume fraction above 20% is beneficial for enhancing tensile strength and yield strength at high temperatures,but it has an adverse effect on room temperature ***,if the reinforcement volume fraction is below 20%,it can improve high-temperature elongation when the temperature exceeds 600℃.

关键词： titanium matrix composites microstucture microhardness tensile properties in-situ synthesis

Chinese Population Reference Curves for Ultrasound-Measured Amniotic Fluid Deepest Vertical Pocket in Dichorionic Twin Pregnancies,and Their Associations With Pregnancy Outcomes

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Maternal-Fetal Medicine 2024年第1期6卷 29-36页

作者： Zhengxin Lyu Tianchen Wu Shan Lu Pengbo yuan Yangyu zhao yuan Wei Department of Obstetrics and Gynecology Peking University Third HospitalBeijing 100191China

Objective:To establish the Chinese population's amniotic fluid deepest vertical pocket(DVP)reference curves for dichorionic twin pregnancies and to investigate DVP links with adverse perinatal ***:This retrospective cohort study,conducted at Peking University Third Hospital from August 2011 to December 2020,used data from 375 women aged 20 to 45 years who had dichorionic twin pregnancies that were confirmed through first-trimester *** exclusions,reference curves were developed using 318 women with 3,299 DVP scans,and the data analyzed included maternal demographics,pregnancy outcomes,ultrasound measurements,and neonatal *** were assessed via ultrasound at regular intervals and grouped by gestational age(GA)for *** mixed models were used to create amniotic fluid reference *** between abnormalities and adverse perinatal outcomes were examined using Chi-squared or Fisher's exact *** regression provided both crude and adjusted odds ratios,adjusting for pre-pregnancy weight,age,ethnicity,parity,and conception *** was set at P<0.05 with 95%confidence intervals(CI),and the analyses were conducted using SPSS ver.26.0(IBM Corp.,Armonk,NY)and SAS ver.9.4(SAS Institute Inc.,Cary,NC,USA)***:DVP increased from the first trimester to a maximum at 26 weeks(95%confidence interval(CI),2.7–8.3 cm for twin 1 and 2.8–7.9 cm for twin 2)and then decreased gradually toward *** between twins 1 and 2 were significant after 26 weeks(95%CI for twin 1:5.3,5.5;95%CI for twin 2:4.4,4.5;P<0.010).Polyhydramnios of twin 1 increased the risk of large for *** of twin 1 increased the risk of small for *** of twin 2 increased the risk of small for GA,premature birth,and neonatal *** of twin 2 increased the risk of preeclampsia,hypertensive disorder complicating pregnancy,and premature rupture of ***:Reference curves

关键词： Amniotic fluid Amniotic fluid deepest vertical pocket Reference curve Dichorionic twin Pregnancy outcome Ultrasound examination

Electromagnetic scattering and imaging simulation of extremely large-scale sea-ship scene based on GPU parallel technology

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Journal of Electronic Science and Technology 2024年第2期22卷 16-23页

作者： Cheng-Wei Zhang zhi-Qin zhao Wei Yang Li-Lai Zhou Hai-Yu Zhu Southwest China Institute of Electronic Technology Chengdu610036China School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu611731China Tencent Company Shenzhen518054China

Aiming to solve the bottleneck problem of electromagnetic scattering simulation in the scenes of extremely large-scale seas and ships,a high-frequency method by using graphics processing unit(GPU)parallel acceleration technique is *** the implementation of different electromagnetic methods of physical optics(PO),shooting and bouncing ray(SBR),and physical theory of diffraction(PTD),a parallel computing scheme based on the CPU-GPU parallel computing scheme is realized to balance computing ***,a multi-GPU framework is further proposed to solve the computational difficulty caused by the massive number of ray tubes in the ray tracing *** using the established simulation platform,signals of ships at different seas are simulated and their images are achieved as *** is shown that the higher sea states degrade the averaged peak signal-to-noise ratio(PSNR)of radar image.

关键词： Multi graphics processing unit Radar imaging Sea-ship Shooting and bouncing rays

Investigation of stress distribution and damage behavior caused by forced installation of a composite bolted joint with a hole-location error

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Chinese Journal of Aeronautics 2024年第1期37卷 201-217页

作者： Chinan LIU yuan LI Yi CHENG An’an zhao Kunpeng DU Yue SHI Ximing LI Hui CHENG School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China AVIC Xi’an Aircraft Industry Group Company LTD Xi’an 710089China

In this paper,the influence of forced installation caused by a hole-location error on the 3D stress distribution and damage of a composite bolted joint is *** analytical model of stress distributed on composite holes is promoted,in view of non-uniform extrusion caused by forced *** first,non-uniform extrusion of the hole edge caused by forced installation is *** to the contact state,expression of hole deformation is ***,based on Hertz theory,the maximum extrusion load is obtained with help of deformation *** constructing an elastic foundation beam model,3D stress distributed on a hole could be analyzed according to the extrusion ***,stress distribution predicted by the above analytical method is compared with that provided by FE considering composite ***,a forced installation experiment is carried out to analyze the damage distribution of the *** show that a central-symmetrically distributed stress is introduced by the hole-location *** an increment of the error,strength of composite decreases due to extrusion ***,stress presents a concave distribution on the *** the hole-location error exceeding 3%,stress decreases gradually due to failure of *** of holes does not exhibit a centrosymmetric *** damage is mainly distributed on the entrance of the hole at the lower sheet.

关键词： Hole-location error Composite joint Forced installation Stress distribution Damage

Effect of Mn content on microstructure and properties of AlCrCuFeMnx high-entropy alloy

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China Foundry 2024年第2期21卷 147-158页

作者： Ning Wang Kai Ma Qiu-da Li Yu-dong yuan Yan-chun zhao Li Feng School of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050China State Key Laboratory of Advanced Processing and Reuse of Nonferrous Metals Lanzhou 730050China CNNC Nuclear Power Operation and Management Co. Ltd.Haiyan 314300ZhejiangChina

AlCrCuFeMnx(x=0,0.5,1,1.5,and 2)high-entropy alloys were prepared using the vacuum arc melting *** microstructure and mechanical properties of AlCrCuFeMnxwere analyzed and tested by XRD,SEM,TEM,nanoindentation,and electronic universal *** results indicate that the AlCrCuFeMnxhigh-entropy alloy exhibits a dendritic structure,consisting of dendrites with a BCC structure,interdendrite regions with an FCC structure,and precipitates with an ordered BCC structure that form within the ***(Mn)has a strong affinity for dendritic,interdendritic,and precipitate structures,allowing it to easily enter these *** an increase in Mn content,the size of the precipitated nanoparticles in the dendritic region initially increases and then ***,the area fraction initially decreases and then ***,the alloy’s strength and wear resistance decrease,while its plasticity *** Al Cr Cu Fe Mn1.5alloy boasts excellent mechanical properties,including a hardness of 360 HV and a wear rate of 2.4×10^(-5)mm^(3)·N^(-1)·mm^(-1).It also exhibits impressive yield strength,compressive strength,and deformation rates of 960 MPa,1,700 MPa,and 27.5%,respectively.

关键词： high-entropy alloys microstructure mechanical properties wear resistance strengthening mechanisms

Oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions via Prufer transformation

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 191-200页

作者： LI zhi-yu LI Kun CAI Jin-ming QIN Jian-fang ZHENG zhao-wen School of Mathematical Sciences Qufu Normal UniversityQufu 273165China College of Mathematics and Systems Science Guangdong Polytechnic Normal UniversityGuangzhou 510665China

A class of Sturm-Liouville problems with discontinuity is studied in this *** oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions are *** main method used in this paper is based on Prufer transformation,which is different from the classical ***,we give two examples to verify our main results.

关键词： Sturm-Liouville problem interface condition oscillatory solution

Corrosion Behavior of Graphene Nanosheets Reinforced Magnesium Matrix Composites in Simulated Body Fluids

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 525-536页

作者： Liwen Chen Jianhui Jing Lulu Zhang Jing Li Weipeng Chen Limin Li yuan zhao Hua Hou Yuhong zhao School of Materials Science and Engineering Collaborative Innovation Center of Ministry of Education and Shanxi Province for High-Performance Al/Mg Alloy MaterialsNorth University of ChinaTaiyuan 030051China Shanxi Key Laboratory of Advanced Manufacturing Technology School of Mechanical EngineeringNorth University of ChinaTaiyuan 030051China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China

Magnesium(Mg)alloy is considered as a promising biodegradable implant material but restricted to rapid ***,the new strategies based on thixomolding process had been explored to utilize the outstanding anti-permeability of graphene nanosheets(GNPs)while inhibit its galvanic corrosion with the matrix,so as to improve the corrosion resistance of *** agglomerate of GNPs with 0.9 wt%content is the main reason for the deterioration of corrosion performance due to the formation of micro-galvanic *** grain refinement of composites with 0.6 wt%content had positive effects on the better corrosion *** process adjusting,the unique distributions of GNPs along grain boundaries play a vital role in improving the corrosion *** can be ascribed to the following mechanisms:(I)The barriers can be established between the Mg matrix and corrosive medium,hence blocking the charge transfer at the interface;(II)The GNPs can effectively promote apatite deposition on the Mg matrix,leading to form dense apatite layers and prevent the further invasion of SBF;(III)The GNPs acting as reinforcements exists in the corrosion layer and apatite layer,impede the apatite layer falling off from the Mg *** findings broaden the horizon for biomedical applications in Mg matrix composites to realize desired performances.

关键词： Magnesium matrix composite Graphene nanosheets Corrosion resistance

Effectively improving the extreme-pressure capacity of a class of intercalated zirconium phosphate materials

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Science China(Technological Sciences) 2024年第3期67卷 753-764页

作者： NIU WenXing zhao XinRui yuan Min HOU zhiGuo LIU Lei XU Hong DONG JinXiang Shanxi Key Laboratory of Chemical Product Engineering Cllege of Chemical Engineering and TechnologyTaiyuan University of TechnologyTaiyuan 030024China School of Chemical and Environmental Engineering Pingdingshan UniversityPingdingshan 467000China

We studied different long-chain ammonium ions intercalated zirconium phosphate α-ZrP, methylamine intercalated ZrP(MAZrP), tetramethylammonium hydroxide intercalated ZrP(TMAH-ZrP), dodecyltrimethylammonium bromide intercalated ZrP(DTAB-ZrP), and stearyl trimethyl ammonium bromide intercalated ZrP(STAB-ZrP) as grease co-additives in combination with isobutylene sulfide(SIB). The grease with co-additives displayed excellent extreme-pressure and anti-wear ***, the combination of the longest chain ammonium ion intercalated zirconium phosphate, STAB-ZrP/SIB, had the best tribological properties. In comparison to α-ZrP, the advantage of STAB-ZrP was that it did not form a large area of the dense physical film like α-ZrP on the worn surface, but rather gave the SIB a chance to contact with the fresh metal surface to generate a chemical film. Therefore, the sub-micron physical film and nanoscale chemical film always exist side by side on the contact surface during the friction process. This intercalated α-ZrP/SIB additive has great potential for use in harsh operating conditions.

关键词： intercalatedα-ZrP/SIB physical film chemical film tribological properties

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The Fabrication and Detection Performance of High Sensitivity Au-Ag Alloy Nanostar/Paper Flexible Surface Enhanced Raman Spectroscopy Sensors

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 436-443页

作者：邓芷盈 WANG Tianyi CAO Shiyi zhao yuan HAN Xiaoyu 张继红谢俊 State Key Laboratory of Silicate Materials for Architectures Department of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Hainan Institute of Wuhan University of Technology Sanya 572000China International School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Hepu Research Center for Silicate Materials Industry Technology Beihai 536100China

Au-Ag alloy nanostars based flexible paper surface enhanced Raman spectroscopy sensors were fabricated through simple nanostar coating on regular office paper,and the surface enhanced Raman spectroscopy detection performances were investigated using crystal violet dye ***-Ag nanostars with sharp tips were synthesized via metal ions reduction *** electron microscope images,X-Ray diffraction pattern and energy dispersive spectroscopy elemental mapping confirmed the nanostar geometry and Au/Ag components of the ***-Vis-NIR absorption spectrum shows wide local surface plasmon resonance induced optical *** addition,finite-difference time-domain simulation shows much stronger electromagnetic field from nanostars than from sphere *** effect of coating layer on Raman signal intensities was discussed,and optimized 5-layer coating with best Raman signal was *** Au-Ag nanostatrs homogeneously distribute on paper fiber *** detection limit is 10-10 M,and the relationship between analyte concentrations and Raman signal intensities shows well linear,for potential quantitative *** calculated enhancement factor is 4.795×10^(6).The flexible paper surface enhanced Raman spectroscopy sensors could be applied for trace chemical and biology molecule detection.

关键词： surface-enhanced raman gold-silver alloy nanostars paper-based SERS sensor flexibility