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Atomistic study of inverse size effect induced by interfacial plasticity in pearlitic multi-principal element alloy

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Rare Metals 2024年第7期43卷 3341-3355页

作者： Chen yang Qiao-sheng Xia Cun-Hong Yin Dong-Peng hua College of Mechanical Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Advanced Manufacturing Technology Ministry of EducationGuizhou UniversityGuiyang 550025China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China

Owing to the fine nano-laminated structure,the pearlitic multi-principal element alloy(PMPEA) exhibits excellent mechanical and tribological ***,the incomplete understanding of the size effect of its lamella thickness and the unclear understanding of the plasticity-interface interaction mechanism limit further optimization of *** this study,the FeCoNi/Ni_3Ti interface-mediated plastic deformation behavior in PMPEA and the variation of mechanical and tribological properties with lamella thickness within the nanoscale range using molecular dynamics(MD) simulation were *** results indicate that the mechanical and tribological properties of the PMPEA with lamella thicknesses below 10 nm have a significant inverse size effect,i.e.,the smaller the lamella thickness,the weaker the *** is because the plastic carrier-interface interaction mechanism changes from a strengthening mechanism that hinders dislocations to a weakening mechanism that promotes dislocations with the decreases in the lamella thickness,and the weakening effect becomes more pronounced as the lamella thickness decreases and the number of interfaces *** particular,the deformation behavior of Ni_3Ti lamellae changes from crystal-like to amorphous-like with decreasing ***,in the sample with larger lamella thickness,the occurrence of hierarchical slips in the body-centered cubic(BCC) phase due to the multiprincipal elements effect can better alleviate the stress concentration caused by the dislocation accumulation at the interface,so that the phase interface exhibits outstanding load-bearing *** the dislocation pattern in BCC phase shows a firm high-density cell,which makes the substrate exhibit a stable tribological response.

关键词： Multi-principal element alloy Nano-laminated structure Molecular dynamics simulation Nanoindentation and nanoscratch

EFFECTS OF NH_4Cl ON THE INTERACTION BETWEEN POLY(ETHYLENE OXIDE) AND IONIC SURFACTANTS IN AQUEOUS SOLUTIONS

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Chinese Journal of Polymer Science 2008年第1期26卷 31-37页

作者： Li, Jing Li, hua-zhen yang, Hai-yang Zhu, Ping-ping He, Ping-sheng Univ Sci & Technol China Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The interaction of poly(ethylene oxide)(PEO)with the ionic surfactants,sodium dodecylsulfate(SDS)and cetyltrimethylammonium chloride(CTAC)respectively,in aqueous solutions containing a certain concentration of NH_4Cl, is studied by the viscosity *** has been found that the ion-dipole interaction between PEO and ionic surfactants is changed considerably by the organic *** anionic suffactant of SDS,the addition of NH_4Cl into solution strengthens the interaction between PEO and the headgroup o...

关键词： Viscosity Ion-dipole interaction Non-ionic polymer Ionic surfactant NH_4Cl

Influence of Rare Earth on Property of Low Chromium Semi-Steel

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Journal of Iron and Steel Research International 2003年第3期10卷 50-53页

作者： LIUJian-hua XIEDan-yang LIChang-sheng SHAOLi ZHANGRui-jun YanshanUniversity Qinhuangdao066004China JiangsuUniversity Zhenjiang212013China HebeiNormalCollege Shijiazhuang050012China

The influence of rare earth( RE) content on mechanical properties and abrasion resistance of low chromium semi-steel was studied by means of metallographic examination,scanning electron microscopic examination and mechanical property test. The experiment results show that RE can improve the comprehensive properties,especially in combination with proper heat treatment. The optimum properties of low chromium semi-steel modified by RE of 0. 25 % could be obtained by normalization at 950 ℃ for 3 h. The main reason is the change in morphology and distribution of eutectic carbide and the precipitation of granular carbides.

关键词： rare earth low chromium semi-steel eutectic carbide precipitation granular carbide

Influence of Interfacial Enantiomeric Grafting on Melt Rheology and Crystallization of Polylactide/Cellulose Nanocrystals Composites

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Chinese Journal of Polymer Science 2022年第1期40卷 93-106页

作者： hua-Gao Fang Kang-Jie yang Qi-Zheng Xie Xu Chen sheng-Li Wu Yun-sheng Ding Department of Polymer Science and Engineering School of Chemistry and Chemical EngineeringHefei University of TechnologyHefei 230009China Anhui Province Key Laboratory of Advanced Functional Materials and Devices Hefei 230009China Anhui Institute for Food and Drug Control Hefei230051China

Incorporating the surface-grafted cellulose nanocrystals(CNCs)with enantiomeric polylactide(PLLA or PDLA)is an effective and sustainable way to modify PLLA,but their difference in promoting matrix crystallization is still *** this study,the CNCs with identical content and length of PLLA and PDLA(CNC-g-L and CNC-g-D)were prepared and blended with *** rheological properties of PLLA/CNC-gD are greatly improved,indicating that the stereocomplexation can significantly improve the interfacial strength as compared with the conventional van der Waals force in PLLA/***,the matrix crystallizes at a higher rate in PLLA/CNC-g-L than PLLA/***/CNC-g-L15 reaches its half crystallinity in 8.26 min while a longer period of 13.41 min is required for PLLA/*** observation reveals that the superior crystallization behavior in PLLA/CNC-g-L is originated from its higher nucleation efficiency and faster growth *** formation of low content of sc-PLA at the interface can restrict the diffusion of PLLA but contribute less to generate crystalline nuclei,which synergistically leads to the retarded crystallization kinetics in PLLA/*** the mechanism of different interfacial enantiomeric grafting on the melt rheology and crystallization of PLLA is of great significance for the development of high-performance polylactide materials.

关键词： Cellulose nanocrystal Polylactide nanocomposite Interfacial stereocomplexation Crystallization Rheology

Microstructures and Mechanical Properties of Helical Bevel Gears Made by Mn-Cu Alloyed Austempered Ductile Iron

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Journal of Iron and Steel Research International 2012年第2期19卷 36-42页

作者： LIU sheng-fa CHEN yang CHEN Xin MIAO hua-ming School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 Hubei China

Austempered ductile iron （ADI） has several advantages of replacing cast steel and forged steel in many engineering fields. A new Mn-Cu alloyed ADI with excellent mechanical properties has been developed in order to cut the cost and enlarge the application of ADI. The helical bevel gears were made of the new-developed Mn-Cu alloyed ADI. The microstructure and mechanical properties of the standard sample were investigated by optical microscope （OM）, scanning electron microscope （SEM） and performance measurement. The results showed that after a series of treatments, the mechanical properties （Rm 1007. 4 to 1200 MPa, A 5.2% to 8. 8%, HRC 32 to HRC 35, O^K 70 to 120 J/cmz ） of the Mn-Cu alloyed ADI standard sample could reach European standard EN1564-97/ EN-CJS-1000-5. The surface hardness after helical bevel gears meshing was significantly increased due to the formation of martensite. The bench test and traffic running testing results suggested that the new Mn-Cu alloyed ADI with ultimate life and median life respectively exceeding 30×104 and 50 × 10^4 times could replace 20CrMnTi forged steel for manufacturing the EQ140 helical bevel gears.

关键词： ADI Mn mechanical property helical bevel gear

Synthesis of Cellulose Tris (4-Methylbenzoate) as Gas Chromatographic Stationary Phase and its Characterization

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Chinese Chemical Letters 2001年第9期12卷 803-806页

作者： Jie hua SHI Gen sheng yang Yun Feng ZHENG College of Chemical Engineering Zhejiang University of Technology Hangzhou 310032

The cellulose tris (4-methylbenzoate) has been synthesised by the catalytic method and was supported at Gas Chrom Q. The absorption capability of cellulose tris (4-methylbenzoate) used as a gas chromatographic stationary phase was characterized by chromatographic method and the Clausius-Clapeyron equation. However, n-alcohols (C-1-C-8) were successfully separated on the column packed with Gas Chrom Q coated with cellullose tris (4-methylbenzoate).

关键词： Cellulose tris(4-methylbenzoate) chromatographic stationary phase absorption heat alcohol

Cryosphere water resources supply function and service in China

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Advances in Climate Change Research 2022年第3期13卷 408-420页

作者： Kai-Lu LI Ren-sheng CHEN Guo-hua LIU Yong yang Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhou 730000China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China College of Urban and Environmental Sciences Northwest UniversityXi’an 710000China

With global warming and rapid shrinkage of the cryosphere,the decreasing cryosphere water resources(CWR)supply function would weaken its service and then affect local economic development and implement of United Nations Sustainable Development Goals(SDGs)in the world,but how does the CWR supply affect its service and their variations in the past and future are still not clear at *** this study,the past dynamics(1960-2020),current situation(2010s)and projected changes(2020-2100)of CWR in China were assessed by calculating the meltwater from glacier,snow cover and the ground ice of permafrost under Representative Concentration Pathways scenarios(RCP2.6,RCP4.5,and RCP8.5).Combined with projected data of population and economy,the CWR service potential was also estimated in the 2030s,2050s and 2090s under scenarios of Shared Socioeconomic Pathways(SSP1,SSP2,and SSP5).The annual CWR in China is about 310.7×10^(9)m^(3) in the 2010s,with glacier runoff,snowmelt,and ground ice meltwater accounting for 24.1%,72.7%and 3.2%,*** SSP1-RCP2.6,the quantity of CWR was projected to decline by 14%-18%over the next 80 years,and the service potential would reach the peak in *** under SSP5-RCP8.5,CWR would be reduced by 40%by 2100,and the service would gradually decline from *** study of CWR is of great significance for water security,sustainable development and risk avoidance in the arid endorheic region.

关键词： Cryosphere water resources Glaciers Snow cover Permafrost Function and service

Microstructural evolution in electroformed nickel shaped-charge liners with nano-sized grains undergone deformation at ultrahigh strain rate

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 617-623页

作者： Feng yang Chun-hua Li sheng-wei Cheng Lei Wang Wen-huai Tian School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Nickel shaped-charge liners with nano-sized grains were prepared by the electroforming technique, and the deformation at ultrahigh strain rate was performed by explosive detonation. The as-formed and post-deformed microstructures of electroformed nickel shaped-charge liners with nano-sized grains were observed by means of transmission electron microscopy, and the orientation distribution of the grains was analyzed by the electron backscattering pattern （EBSP） technique. The melting phenomenon in the jet fragment and the recovery and recrystallization in the slug after plastic deformation at ultrahigh-strain rate were observed in the ultrafine-grained nickel shaped-charge liners. The research evidence shows that dynamic recovery and recrystallization play an important role in plastic deformation at ultrahigh strain rate.

关键词： electroformed nickel nanosized plastic deformation electroformation microtexture dynamic recovery and recrystallization

Predicting Glass Transition Temperature of Polyethylene/Graphene Nanocomposites by Molecular Dynamic Simulation

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Chemical Research in Chinese Universities 2013年第4期29卷 788-792页

作者： sheng Yan-zhen yang hua LI Jun-yin SUN Miao Tianjin Key Laboratory of Structure and Performance for Functional Molecules Key Laboratory of Inorganic-organic Hybrid Functional Material Chemistry Ministry of Education College of Chemistry Tianjin Normal University Tianjin 300387 P. R. China School of Chemical and Environmental Engineering Harbin University of Science and Technology Harbin 150080 P. R. China

The glass transition temperature of polyethylene/graphene nanocomposites was investigated by molecular dynamic simulation. The specific volumes of three systems（polycthylene, polyethylene with a small graphene sheet and two small graphene sheets） were examined as a function of temperature. We found that the glass transition temperature decreases with increasing graphene. Then the van der Waals energy changes obviously with increasing graphene and the torsion energy also plays an important role in the glass transition of polymer. The radial distribution functions of the inter-molecular carbon atoms suggest the interaction between PE and graphene weakens with increasing graphene. These indicate that graphene can prompt the motion of chain segments of polymer and decrease the glass transition temperature （Tg） of polymer.

关键词： Molecular dynamic simulation Glass transition Polyethylene Graphene